Toe joint replacement models

ABSTRACT

In various embodiments, provided are implantable devices for replacing all or a portion of a metatarsophalangeal joint, comprising (i) a metatarsal component comprising a substantially convex bearing surface; or (ii) a phalanx component comprising a substantially concave bearing surface; or (iii) both. In various embodiments, also provided are methods of treating hallux valgus by replacing all or a portion of a metatarsophalangeal joint with one or more of the provided implantable devices.

CROSS REFERENCE TO RELATED APPLICATION

This application claims priority to and any other benefit of U.S.Provisional Patent Application Ser. No. 61/163,920, filed Mar. 27, 2009,the entirety of which is incorporated by reference herein.

BACKGROUND

Hallux valgus is characterized as a deformity of the great toe (hallux)and first metatarsophalangeal joint, wherein the first metatarsal ismedially deviated, the great toe is laterally deviated and/or rotated onthe head of the metatarsal, the plantar pad and sesamoids are displacedwith the toe, and the ligaments on the medial side of themetatarsophalangeal joint are stretched. The position of the great toewith respect to the second toe can be overriding, underriding, abutting,or without contact. Thus, hallux valgus can involve transverse planedeformities (hallux abductus), or frontal and transverse planedeformities (hallux abductovalgus). With respect to deformities in thetransverse plane, the angle between the longitudinal axis of themetatarsals of the first and second toes (intermetatarsal angle)typically deviates beyond the normal range of 8-12°. With respect todeformities in the frontal plane, the angle between the longitudinalaxis of the metatarsal and proximal phalanx of the great toe (halluxvalgus angle) typically deviates beyond the normal upper limit of15-20°.

In addition to physical deformity, hallux valgus is often accompanied byformation of a callous, bursa, or bunion over the first metatarsal head,pain in the first metatarsophalangeal joint during ambulation, pain inthe metatarsal head, and combinations thereof.

Hallux valgus is estimated to affect more than 43 million people in theUnited States, with incidence more predominate in females, those olderthan 60 years of age, teenagers who wear high heels, and athletes. Itcan develop due to numerous factors, including biomechanical instability(e.g., excessive protonation), arthritic/metabolic conditions (e.g.,osteo/rheumatoid arthritis), neuromuscular disease (e.g., multiplesclerosis), trauma (e.g., soft-tissue sprains, dislocations, andsports-related injuries), and structural deformities (e.g., abnormalmetatarsal length). Additionally, there tends to be familial dispositionto developing hallux valgus.

Development of hallux valgus typically occurs in four stages. See Root,M L, “Normal and Abnormal Function of the Foot,” Vol. 2, ClinicalBiomechanics (1977). The first stage is associated with lateralsubluxation (partial or complete dislocation) of the proximal phalanx.The second stage is associated with increased abduction of the hallux inthe transverse and/or frontal planes. The third stage is associated withadditional subluxation at the first metatarsophalangeal joint. Thefourth stage is associated with dislocation of the firstmetatarsophalangeal joint.

Hallux valgus is a complex deformity and various approaches to treatingor correcting the deformity may be available. For example, when halluxvalgus is in its early stages, or where surgical correction iscontraindicated, braces, straps, splints, orthotics, or combinationsthereof may be used to manage progression of the deformity and relievethe associated symptoms. However, surgery is the only means ofcorrecting the deformity.

The first surgical treatment to address hallux valgus dates to 1881 whenan osteotomy procedure involving an incision medial to the extensorhallucis longus, followed by incision of the periosteum, removal ofexostosis, removal of bone from behind the caputulum of the metatarsus,and suturing of the bone. Since this forerunning procedure, numerousother procedures have been developed, all with the goal of addressingthe deformity with minimal complications. Such surgical procedures,while varying depending upon the nature of the deformity and particularneeds of the patient, generally allow for establishment of a congruousfirst metatarsophalangeal joint, reduction of the intermetatarsal angle,realignment of the sesamoids, realignment of the hallux to a rectus(rather than an abductus) position, and maintenance or increase of therange of motion of the first metatarsophalangeal joint.

Typical surgical procedures involve one or more of osteotomy of themetatarsal head, osteotomy of the metatarsal shaft or base, fusion ofthe metatarsophalangeal joint, resectional arthroplasty, resectionalarthroplasty with a partial (hemi) implant, and resectional arthroplastywith a total implant. With respect to procedures involving an implant,numerous devices for use therewith are known in the art. For example,known hemi arthroplasty devices, which are typically used when theproximal phalanx is degenerated but the metatarsal head is intact,include the BioPro® hemi toe implant (BioPro, Inc., Port Huron, Mich.);Futura™ Metal Hemi Toe implant (Tornier, Edina, Minn.); K2™ Hemi ToeImplant System (Integra LifeSciences Corp., Plainsboro, N.J.); andSwanson™ Great Toe Implant (Wright Medical Technology, Inc., Arlington,Tenn.), all of which are depicted in FIG. 1A. Examples of knowndouble-stemmed hinges, which are typically used when both the proximalphalanx and the metatarsal head are degenerated, include the Swanson™Flexible Hinge Toe implant (Wright Medical Technology, Inc., Arlington,Tenn.); GAIT Implant™ (Sgarlato Med, San Jose, Calif.); and Futura™Flexible Great Toe implant (Tornier, Edina, Minn.), all of which aredepicted in FIG. 1B. In addition, examples of known two-componentdevices, which are also typically used when both the proximal phalanxand the metatarsal head are degenerated, include the Total Toe™ System(Biomet, Warsaw, Ind.); Bio-Action™ Great Toe Implant (Osteomed, Inc.,Addison, Tex.); ReFlexion™ 1^(st) MPJ Implant System (Osteomed, Inc.,Addison, Tex.); and KGTI™ Kinetik Great Toe Implant System (IntegraLifeSciences Corp., Plainsboro, N.J.), all of which are depicted in FIG.1C.

Along with the knowledge in the art of numerous implant devices is theknowledge of numerous problems associated with such devices. Examplesinclude, but are not limited to, shearing stress, loosening of thedevice, fragmentation, fracture through the proximal phalanx, breakageof hinged implants at the hinge, misalignment, recurrence of deformity,limited joint motion, development of plantar keratosis, development oftenderness around the joint, development of long flexor tendonitis,development of metatarsalgia, and development of metallosis.Accordingly, there is need in the art for improved implant devices foruse in correcting hallux valgus. Moreover, there is need in the art fordevices that are aligned and articulate in a manner consistent withnatural motion of the metatarsophalangeal joint, that resist torsionforces applied to the device, and that are designed to be implantedwithout complex assembly, positioning, or other manipulation by thesurgeon.

SUMMARY

Embodiments of the present invention provide novel implantable devicesused to replace all or a portion of a joint of the human toe. In someembodiments, the implantable devices are designed to replace all or aportion of the metatarsophalangeal joint. In some embodiments, thedevices replace all or a portion of the metatarsal head and function asthe metatarsal component of the metatarsophalangeal joint. In someembodiments, the devices replace all or a portion of the proximal end ofthe proximal phalanx and function as the phalanx component of themetatarsophalangeal joint.

In various embodiments, the implantable devices replace all or a portionof a metatarsophalangeal joint and comprise (i) a metatarsal componentfor surgical implantation into the distal end of a metatarsal bone,comprising a metatarsal articulation member comprising a substantiallyconvex bearing surface; or (ii) a phalanx component for surgicalimplantation into the proximal end of a proximal phalanx bone,comprising a phalanx articulation member comprising a substantiallyconcave bearing surface; or (iii) a metatarsal component for surgicalimplantation into the distal end of a metatarsal bone, comprising ametatarsal articulation member comprising a substantially convex bearingsurface; and a phalanx component for surgical implantation into theproximal end of a proximal phalanx bone, comprising a phalanxarticulation member comprising a substantially concave bearing surface.In some embodiments, the metatarsal component and the phalanx componentare adapted to cooperatively engage when implanted such that themetatarsal articulation member and the phalanx articulation member maymove with respect to each other and collectively serve as a prostheticmetatarsophalangeal joint.

In various embodiments, also provided are methods of treating halluxvalgus, comprising replacing all or a portion of a metatarsophalangealjoint with implantable devices selected from: (i) a metatarsal componentfor surgical implantation into the distal end of a metatarsal bone,comprising a metatarsal articulation member comprising a substantiallyconvex bearing surface; (ii) a phalanx component for surgicalimplantation into the proximal end of a proximal phalanx bone,comprising a phalanx articulation member comprising a substantiallyconcave bearing surface; or (iii) a metatarsal component for surgicalimplantation into the distal end of a metatarsal bone, comprising ametatarsal articulation member comprising a substantially convex bearingsurface; and a phalanx component for surgical implantation into theproximal end of a proximal phalanx bone, comprising a phalanxarticulation member comprising a substantially concave bearing surface.

These and additional features of the invention will become apparent inthe course of the following detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete appreciation of the invention and the many embodimentsthereof will be readily obtained as the same becomes better understoodby reference to the following detailed description when considered inconnection with the accompanying drawings, wherein:

FIG. 1 illustrates various examples of implantable devices known in theart;

FIGS. 2-4 illustrate one example of an implantable two-component deviceand elements thereof;

FIGS. 5-7 illustrate an additional example of an implantabletwo-component device and elements thereof;

FIGS. 8-10 illustrate a further example of an implantable two-componentdevice and elements thereof;

FIGS. 11-13 also illustrate one example of an implantable two-componentdevice and elements thereof;

FIGS. 14-16 illustrate an additional example of an implantabletwo-component device and elements thereof;

FIGS. 17-19 illustrate a further example of an implantable two-componentdevice and elements thereof;

FIGS. 20-22 also illustrate an example of an implantable two-componentdevice and elements thereof;

FIGS. 23-25 illustrate an additional example of an implantabletwo-component device and elements thereof;

FIGS. 26-27 illustrate a further example of an implantable two-componentdevice and elements thereof;

FIGS. 28-30 also illustrate one example of an implantable two-componentdevice and elements thereof;

FIG. 31 illustrates the bones of the foot, including those most relevantto hallux valgus: A, distal phalanx; B, interphalangeal joint; C,proximal phalanx; D, metatarsophalangeal joint; E, metatarsal; and

FIG. 32 illustrates deformity of the A, hallux valgus angle; and B,intermetatarsal angle. In various embodiments, the provided implants aredesigned to correct one or both angles in a subject foot.

DETAILED DESCRIPTION

The present invention will now be described with occasional reference tothe specific embodiments of the invention. This invention may, however,be embodied in different forms and should not be construed as limited tothe embodiments set forth herein. Rather, these embodiments are providedso that this disclosure will be thorough and complete, and will fullyconvey the scope of the invention to those skilled in the art.Similarly, the present invention should not be considered limited to thespecific examples described herein, but rather should be understood tocover all aspects of the invention. Various modifications andequivalents, as well as numerous structures and devices to which thepresent invention may be applicable will be readily apparent to those ofskill in the art. Those skilled in the art will understand that variouschanges may be made without departing from the scope of the invention,which is not to be considered limited to what is described in thespecification.

Unless otherwise defined, all technical and scientific terms used hereinhave the same meaning as commonly understood by one of ordinary skill inthe art to which this invention belongs. The terminology used in thedescription of the invention herein is for describing particularembodiments only and is not intended to be limiting. As used in thedescription of the invention and the appended claims, the singular forms“a,” “an,” and “the” are intended to include the plural forms as well,unless the context clearly indicates otherwise.

Unless otherwise indicated, all numbers expressing quantities ofingredients, properties such as molecular weight, reaction conditions,and so forth as used in the specification and claims are to beunderstood as being modified in all instances by the term “about.”Additionally, the disclosure of any ranges in the specification andclaims are to be understood as including the range itself and alsoanything subsumed therein, as well as endpoints. Unless otherwiseindicated, the numerical properties set forth in the specification andclaims are approximations that may vary depending on the desiredproperties sought to be obtained in embodiments of the presentinvention. Notwithstanding that numerical ranges and parameters settingforth the broad scope of the invention are approximations, the numericalvalues set forth in the specific examples are reported as precisely aspossible. Any numerical values, however, inherently contain certainerrors necessarily resulting from error found in their respectivemeasurements.

Provided are implantable devices used to replace all or part of a humantoe joint. In some embodiments, the devices replace all or a portion ofthe metatarsophalangeal joint, said devices being designed to bepositioned during implantation such that when the muscles and tendons ofthe foot exert a force on the natural phalanx and metatarsal bones, thecomponents of the device provide functional cooperation that emulatesthe desired and permissible movements of the metatarsophalangeal joint.In some embodiments, the provided devices align and articulate in amanner consistent with natural motion of the joint. In some embodiments,the devices are adapted to be implanted without complex assembly,positioning, or other manipulation by the surgeon.

In various embodiments, the implantable devices replace all or a portionof a metatarsophalangeal joint and comprise (i) a metatarsal componentfor surgical implantation into the distal end of a metatarsal bone,comprising a metatarsal articulation member comprising a substantiallyconvex bearing surface; or (ii) a phalanx component for surgicalimplantation into the proximal end of a proximal phalanx bone,comprising a phalanx articulation member comprising a substantiallyconcave bearing surface; or (iii) a metatarsal component for surgicalimplantation into the distal end of a metatarsal bone, comprising ametatarsal articulation member comprising a substantially convex bearingsurface; and a phalanx component for surgical implantation into theproximal end of a proximal phalanx bone, comprising a phalanxarticulation member comprising a substantially concave bearing surface.Accordingly, these devices can be used for total joint replacement whena metatarsal and a phalanx component are implanted, or for partial(hemi) replacement when only one of the metatarsal and phalanx componentis implanted.

In various embodiments, the implantable devices replace all or a portionof a metatarsophalangeal joint and comprise: (i) a metatarsal componentfor surgical implantation into the distal end of a metatarsal bone,comprising a metatarsal articulation member comprising a substantiallyconvex bearing surface; a base member adapted to be fixed within themetatarsal bone; and a locking member adapted to mechanically join themetatarsal articulation member to the base member; and (ii) a phalanxcomponent for surgical implantation into the proximal end of a proximalphalanx bone, comprising a phalanx articulation member comprising asubstantially concave bearing surface; a base member adapted to be fixedwithin the phalanx bone; and a locking member adapted to mechanicallyjoin the phalanx articulation member to the base member; wherein themetatarsal component and the phalanx component are adapted tocooperatively engage when implanted such that the metatarsalarticulation member and the phalanx articulation member may move withrespect to each other and collectively serve as a prostheticmetatarsophalangeal joint.

In various embodiments, the implantable devices replace all or a portionof a metatarsophalangeal joint and comprise: (i) a metatarsal componentfor surgical implantation into the distal end of a metatarsal bone,comprising a metatarsal articulation member comprising a substantiallyconvex bearing surface; and a locking member comprising a screw threadadapted to fix the metatarsal component in the metatarsal bone; and (ii)a phalanx component for surgical implantation into the proximal end of aproximal phalanx bone, comprising a phalanx articulation membercomprising a substantially concave bearing surface; and a locking membercomprising a screw thread adapted to fix the phalanx component in thephalanx bone; wherein the metatarsal component and the phalanx componentare adapted to cooperatively engage when implanted such that themetatarsal articulation member and the phalanx articulation member maymove with respect to each other and collectively serve as a prostheticmetatarsophalangeal joint.

In various embodiments, the implantable devices replace all or a portionof a metatarsophalangeal joint and comprise: (i) a metatarsal componentfor surgical implantation into the distal end of a metatarsal bone,comprising a metatarsal articulation member comprising a substantiallyconvex parabolic bearing surface terminating at equidistantly positionedends; and (ii) a phalanx component for surgical implantation into theproximal end of a proximal phalanx bone, comprising a phalanxarticulation member comprising a substantially concave bearing surface;wherein the metatarsal component and the phalanx component are adaptedto cooperatively engage when implanted such that the metatarsalarticulation member and the phalanx articulation member may move withrespect to each other and collectively serve as a prostheticmetatarsophalangeal joint.

The provided devices may be comprised of any material suitable forimplant devices. For example, materials that comply with ASTM F75-01,F90-01, F136-02a, and other applicable specifications. In someembodiments suitable materials of composition may be selected fromultra-high molecular weight polyethylene (“UHMWPE”), stainless steel(including but not limited to SS 316L), titanium, titanium alloys(including but not limited to Ti-6Al-4V), chromium-cobalt-molybdenumalloys, pyrocarbon, and combinations thereof. Properties of somesuitable materials are shown in Table 1. In some embodiments, a devicemay comprise a coating for enhancing bone growth. For example, asuitable coating may be titanium plasma spray. In some embodiments, adevice may be partially or completely formed from pyrocarbon. In someembodiments, the pyrocarbon is coated with titanium plasma spray. Insome embodiments, UHMWPE is the material of composition used for themetatarsal bearing surface, the phalanx bearing surface, or both.

TABLE 1 Elastic Tensile Modulus Yield Material Modulus Strength Densityof Shear Strength UHMWPE  1258 MPa 45.8 MPa   932 kg/m3 11-13 Mpa  23.56 MPa   Stainless   200 GPa 485 MPa 8027 kg/m3 82 GPa 170 MPa Steel316L Ti-6Al-4V 113.8 GPa 950 MPa 4430 Kg/m3 44 GPa 880 MPa Pyrocarbon  25 GPa 420 MPa 1700 kg/m3 — 345 MPa

Referring to FIGS. 2-10, illustrated are various examples of implantabledevices of the invention which are designed to replace all or a portionof a metatarsophalangeal joint. Such devices comprise one or more of:(i) a metatarsal component for surgical implantation into the distal endof a metatarsal bone, comprising a metatarsal articulation membercomprising a substantially convex bearing surface and a stem adapted toreceive a portion of a locking member; a base member adapted to be fixedwithin the metatarsal bone, the base member comprising a cavity adaptedto receive at least a portion of the stem and a portion of the lockingmember; and a locking member adapted to be received by the stem andcavity; wherein when the stem is received in the cavity and the lockingmember is received by the stem and cavity, the metatarsal articulationmember is mechanically joined to the base member; and (ii) a phalanxcomponent for surgical implantation into the proximal end of a proximalphalanx bone, comprising a phalanx articulation member comprising asubstantially concave bearing surface and a stem adapted to receive aportion of a locking member; a base member adapted to be fixed withinthe phalanx bone, the base member comprising a cavity adapted to receiveat least a portion of the stem and a portion of the locking member; anda locking member adapted to be received by the stem and cavity; whereinwhen the stem is received in the cavity and the locking member isreceived by the stem and cavity, the phalanx articulation member ismechanically joined to the base member.

In those embodiment wherein one of the components is implanted, thechosen component is adapted to cooperatively engage with and move withrespect to either the proximal end of the proximal phalanx bone or thedistal end of the metatarsal bone. In those embodiments wherein both ofthe components are implanted, the metatarsal component and the phalanxcomponent are adapted to cooperatively engage such that the metatarsalarticulation member and the phalanx articulation member move withrespect to each other and collectively serve as a prostheticmetatarsophalangeal joint.

Referring to FIG. 2, one example of a two-component implant device 1comprises a metatarsal component 2 and a phalanx component 3. Themetatarsal component 2 is designed to be implanted into the distal endof a resected metatarsal bone to replace all or a portion of themetatarsal head and function as the metatarsal component of themetatarsophalangeal joint. The metatarsal component 2 comprises a basemember 4, a metatarsal articulation member 5, and a locking member 6.The base member 4 may be of any suitable length and dimension to allowfor fixation within the metatarsal bone, and may be fixed by anymedically suitable means. In some embodiments, the base member 4 isdesigned to be implanted in approximately one third of the length of themetatarsal bone. In some embodiments, it may be fixed with bone cement.

The phalanx component 3 is designed to be implanted into the proximalend of a resected proximal phalanx bone to replace all or a portion ofthe proximal end of the proximal phalanx and function as the phalanxcomponent of the metatarsophalangeal joint. The phalanx component 3comprises a base member 7, a phalanx articulation member 8, and alocking member 9. The base member 7 may be of any suitable length anddimension to allow for fixation within the phalanx bone, and may befixed by any medically suitable means. In some embodiments, the phalanxcomponent 3 is designed to be implanted in approximately half of thelength of the phalanx bone. In some embodiments, it may be fixed withbone cement.

In some embodiments, one or both of the metatarsal component 2 and thephalanx component 3 are implanted into the human foot to replace all ora portion of the metatarsophalangeal joint. In some embodiments, one orboth components 2, 3 may be implanted in a primary resectionalarthroplasty procedure, in a revision arthroplasty procedure performedto replace or compensate for a failed implant, or combinations thereof.In some embodiments, one or both components 2, 3 are implanted in aprimary resectional arthroplasty procedure. In some embodiments, eachcomponent 2, 3 implanted may be selected from small, medium, or largesizes as necessary to approximate the anatomy of the subject. In someembodiments, the components 2, 3 may comprise one or more dimensions asset forth in Table 2. In some embodiments, each component 2, 3 andelements thereof may be customized to the anatomy of the subject.

TABLE 2 Dimension (mm) Metatarsal Base Member Length 22-26 Base MemberOuter Diameter Top  7-10 Base Member Outer Diameter Bottom  7-10Articulation Member Length 12-16 (Excluding Head Portion) ArticulationMember Outer Diameter Top 4-7 Articulation Member Outer Diameter Bottom3-6 Head Portion Diameter 10-13 Locking Member Outer Diameter 4-7Locking Member Inner Diameter 2-5 Locking Member Thickness 0.5 HeadPortion Height 2   Phalanx Base Member Length 18-22 Base Member OuterDiameter Top 10-13 Base Member Outer Diameter Bottom 10-13 ArticulationMember Length 10-15 (Excluding Head Portion) Articulation Member OuterDiameter Top  7-10 Articulation Member Outer Diameter Bottom 6-8 HeadPortion Diameter 10-13 Locking Member Outer Diameter  7-10 LockingMember Inner Diameter 5-8 Locking Member Thickness 0.5 Head PortionDepth 2  

A further illustrated in FIG. 3, the base member 4 of the metatarsalcomponent 2 is cylindrical and has a generally circular cross-section.However, it is also contemplated that a base member 4 may alternativelybe non-cylindrical, have another suitable cross-section, or combinationsthereof, provided that other elements of the metatarsal component 2 arealso adapted to fit such alternatives. For example, a base member 4 mayhave a cross-section selected from generally elliptical, square,triangular, or other suitable shape. The base member 4 comprises acontinuous first end 11, a non-continuous second end 12, and a cavity 10for receiving a portion of the metatarsal articulation member 5. Thecavity 10 comprises a first end 13 recessed within the base member 4, asecond end 14 that is partially shared with the second end 12 of thebase member 4, and a peripheral slot 15 for receiving a portion of thelocking member 6. As shown, the cavity 10 is generally conical ortapered and has a generally circular cross-section. However, it is alsocontemplated that the cavity 10 may alternatively be non-conical ornon-tapered, have another suitable cross-section, or combinationsthereof, provided that other elements of the metatarsal component 2 arealso adapted to fit such alternatives. For example, a cavity 10 may havea cross-section selected from generally elliptical, square, triangular,or other suitable shape. The slot 15 is integrated with and formedaround all or a portion of the cavity 10 in a direction away from alongitudinal axis 16 of the base member 4. As shown, the slot 15 may bepositioned at or proximate to the first end 13 of the cavity 10, but itis also contemplated that it may alternatively be positioned elsewherealong the cavity 10, provided that the metatarsal articulation member 5is correspondingly adapted. Moreover, it is also contemplated that thefirst end 11 of the base member 4 may alternatively be non-continuousand partially shared with the first end 13 of the cavity 10.

The articulation member 5 of the metatarsal component 2 comprises a headportion 17, a stem 20, and an integral slot 22. The head portion 17comprises a substantially convex bearing surface 18 and a proximalsurface 19 opposite thereto. As shown, the proximal surface 19 isgenerally planar, but it is also contemplated that it could benon-planar. The bearing surface 18 is adapted to emulate the generalshape and function of the head portion of the metatarsal bone within ametatarsophalangeal joint. The stem 20 protrudes from the center (notlabeled) of the proximal surface 19, terminates at a proximal end 21,and is adapted to be received within the cavity 10 of the base member 4.When so received, the proximal surface 19 abuts the second end 12 of thebase member 4. It is also contemplated that the proximal surface 19could be spaced from the second end 12 when so received. As shown, thestem 20 is generally conical or tapered and has a generally circularcross-section. However, it is also contemplated that the stem 20 mayalternatively be non-conical or non-tapered, have another suitablecross-section, or combinations thereof, provided that other elements ofthe metatarsal component 2 are also adapted to fit such alternatives.For example, a stem 20 may have a cross-section selected from generallyelliptical, square, triangular, or other suitable shape. The slot 22 isintegrated with and formed in a direction towards a longitudinal axis 23of the metatarsal articulation member 5 around all or a portion of thestem 20, and it is adapted to receive a portion of the locking member 6.As shown, the slot 22 may be positioned at or proximate to the proximalend 21, but it is also contemplated that it may alternatively bepositioned elsewhere along the stem 20, provided that the base member 4is correspondingly adapted. The stem 20 and slot 22 are adapted to fitwithin the cavity 10 of the base member 4 such that both slots 15, 22are aligned to each receive a portion and together receive the whole ofthe locking member 6.

The locking member 6 is a resilient spring member having at least afirst and a second configuration (not shown) and is adapted to bereceived within both slots 15, 22 to mechanically join the metatarsalarticulation member 5 with the base member 4. In some embodiments, themetatarsal articulation member 5 and the base member 4 are permanentlyjoined, and as such are effectively a single component of theimplantable device. As shown, the locking member 6 is non-continuous andhas a generally circular cross-section. However, it is also contemplatedthat the locking member 6 may alternatively be continuous, have adifferent cross-section, or combinations thereof, provided that otherelements (including, but not limited to the slots 15, 22) of themetatarsal component 2 are correspondingly adapted. For example, alocking member 6 could have a cross-section selected from generallyelliptical, square, triangular, or other suitable cross-section. In someembodiments, the locking member 6 may comprise a resilient materialsuitable for surgical implants.

In some embodiments of assembly, the locking member 6 is flexed from afirst to a second configuration upon insertion through the partiallyshared second ends 12, 14 of the base member 4 and cavity 10; remains inthe second configuration as it is advanced along the cavity 10 towardsthe first end 13; and upon encountering the slot 15 flexes from thesecond to the first configuration as it is received within the slot 15.Alternatively, it is contemplated that the locking member 6 may flexfrom the second to an intermediate third configuration as it is receivedwithin the slot 15.

In some embodiments of assembly, a portion of the locking member 6 isreceived within the slot 22 of the metatarsal articulating member 5; thestem 20 of said articulating member 5 is inserted through the sharedends 12, 14 of the base member 4 and cavity 10 as the locking member 6flexes from a first to a second configuration; the locking member 6remains in the second configuration as it and the stem 20 are advancedalong the cavity 10 towards the first end 13; and upon encountering theslot 15 of the base member 4, the locking member 6 flexes from thesecond to the first configuration as it is received within the slot 15.Alternatively, it is contemplated that the locking member 6 may flexfrom the second to an intermediate third configuration as it is receivedwithin the slot 15.

As further illustrated in FIG. 4, the base member 7 of the phalanxcomponent 3 is cylindrical and has a generally circular cross-section.However, it is also contemplated that a base member 7 may alternativelybe non-cylindrical, have another suitable cross-section, or combinationsthereof, provided that other elements of the phalanx component 3 arealso adapted to fit such alternatives. For example, a base member 7 mayhave a cross-section selected from generally elliptical, square,triangular, or other suitable shape. The base member 7 comprises acontinuous first end 24, a non-continuous second end 25, and a cavity 26for receiving a portion of the phalanx articulation member 8. The cavity26 comprises a first end 27 recessed within the base member 7, a secondend 28 that is partially shared with the second end 25 of the basemember 7, and a peripheral slot 29 for receiving a portion of thelocking member 9. As shown, the cavity 26 is generally conical ortapered and has a generally circular cross-section. However, it is alsocontemplated that the cavity 26 may alternatively be non-conical ornon-tapered, have another suitable cross-section, or combinationsthereof, provided that other elements of the phalanx component 3 arealso adapted to fit such alternatives. For example, a cavity 26 may havea cross-section selected from generally elliptical, square, triangular,or other suitable shape. The slot 29 is integrated with and formedaround all or a portion of the cavity 26 in a direction away from alongitudinal axis 30 of the base member 7. As shown, the slot 29 may bepositioned at or proximate to the first end 27, but it is alsocontemplated that it may alternatively be positioned elsewhere along thecavity 26, provided that the phalanx articulation member 8 iscorrespondingly adapted. Moreover, it is also contemplated that thefirst end 24 of the base member 7 may alternatively be non-continuousand partially shared with the first end 27 of the cavity 26.

The articulation member 8 of the phalanx component 3 comprises a headportion 31, a stem 34, and an integral slot 36. The head portion 31comprises a substantially concave bearing surface 32 and a distalsurface 33 opposite thereto. As shown, the distal surface 33 isgenerally planar, but it is also contemplated that it could benon-planar. The bearing surface 32 is adapted to emulate the generalshape and function of the proximal portion of the proximal phalanx bonewithin a metatarsophalangeal joint. The stem 34 protrudes from thecenter (not labeled) of the distal surface 33, terminates at a distalend 35, and is adapted to be received within the cavity 26 of the basemember 7. When so received, the distal surface 33 abuts the second end25 of the base member 7. It is also contemplated that the distal surface33 could be spaced from the second end 25 when so received. As shown,the stem 34 is generally conical or tapered and has a generally circularcross-section. However, it is also contemplated that the stem 34 mayalternatively be non-conical or non-tapered, have another suitablecross-section, or combinations thereof, provided that other elements ofthe phalanx component 3 are also adapted to fit such alternatives. Forexample, a stem 34 may have a cross-section selected from generallyelliptical, square, triangular, or other suitable shape. The slot 36 isintegrated with and formed around all or a portion of the stem 34 in adirection towards a longitudinal axis 37 of the phalanx articulationmember 8, and it is adapted to receive a portion of the locking member9. As shown, the slot 36 may be positioned at or proximate to the distalend 35, but it is also contemplated that it may alternatively bepositioned elsewhere along the stem 34, provided that the base member 7is correspondingly adapted. The stem 34 and slot 36 are adapted to fitwithin the cavity 26 of the base member 7 such that both slots 29, 36are aligned to each receive a portion and together receive the whole ofthe locking member 9.

The locking member 9 is a resilient spring member having at least afirst and a second configuration (not shown) and is adapted to bereceived within both slots 29, 36 to mechanically join the phalanxarticulation member 8 with the base member 7. In some embodiments, thephalanx articulation member 8 and the base member 7 are permanentlyjoined, and as such are effectively a single component of theimplantable device. As shown, the locking member 9 is non-continuous andhas a generally circular cross-section. However, it is also contemplatedthat the locking member 9 may alternatively be continuous, have adifferent cross-section, or combinations thereof, provided that otherelements (including, but not limited to the slots 29, 36) of the phalanxcomponent 3 are correspondingly adapted. For example, a locking member 9could have a cross-section selected from generally elliptical, square,triangular, or other suitable cross-section. In some embodiments, thelocking member 9 may comprise a resilient material suitable for surgicalimplants.

In some embodiments of assembly, the locking member 9 is flexed from afirst to a second configuration upon insertion through the partiallyshared second ends 25, 28 of the base member 7 and cavity 26; remains inthe second configuration as it is advanced along the cavity 26 towardsthe first end 27; and upon encountering the slot 29 flexes from thesecond to the first configuration as it is received within the slot 29.Alternatively, it is contemplated that the locking member 9 may flexfrom the second to an intermediate third configuration as it is receivedwithin the slot 29.

In some embodiments of assembly, a portion of the locking member 9 isreceived within the slot 36 of the phalanx articulating member 8, thestem 34 of said articulating member 8 is inserted through the sharedends 25, 28 of the base member 7 and cavity 26 as the locking member 9flexes from a first to a second configuration; the locking member 9remains in the second configuration as it and the stem 34 are advancedalong the cavity 26 towards the first end 27; and upon encountering theslot 29 of the base member 7, the locking member 9 flexes from thesecond to the first configuration as it is received within the slot 29.Alternatively, it is contemplated that the locking member 9 may flexfrom the second to an intermediate third configuration as it is receivedwithin the slot 29.

Referring to FIGS. 5-7, illustrated is another example of atwo-component implant 38 that comprises a metatarsal component 39 and aphalanx component 40. The metatarsal component 39 is designed to beimplanted into the distal end of a resected metatarsal bone to replaceall or a portion of the metatarsal head and function as the metatarsalcomponent of the metatarsophalangeal joint. The metatarsal component 39comprises a base member 41, a metatarsal articulation member 42, and alocking member 43. The base member 41 may be of any suitable length anddimension to allow for fixation within the metatarsal bone, and may befixed by any medically suitable means. In some embodiments, the basemember 41 is designed to be implanted in approximately one third of thelength of the metatarsal bone. In some embodiments, it may be fixed withbone cement.

The phalanx component 40 is designed to be implanted into the proximalend of a resected proximal phalanx bone to replace all or a portion ofthe proximal end of the proximal phalanx and function as the phalanxcomponent of the metatarsophalangeal joint. The phalanx component 40comprises a base member 44, a phalanx articulation member 45, and alocking member 46. The base member 44 may be of any suitable length anddimension to allow for fixation within the phalanx bone, and may befixed by any medically suitable means. In some embodiments, the basemember 44 is designed to be implanted in approximately half of thelength of the phalanx bone. In some embodiments, it may be fixed withbone cement.

In some embodiments, one or both of the metatarsal component 39 and thephalanx component 40 are implanted into the human foot to replace all ora portion of the metatarsophalangeal joint. In some embodiments, one orboth components 39, 40 may be implanted in a primary resectionalarthroplasty procedure, in a revision arthroplasty procedure performedto replace or compensate for a failed implant, or combinations thereof.In some embodiments, one or both components 39, 40 are implanted in arevision arthroplasty procedure. In some embodiments, each component 39,40 implanted may be selected from small, medium, or large sizes asnecessary to approximate the anatomy of the subject. In someembodiments, the components 39, 40 may comprise one or more dimensionsset forth in Table 3. In some embodiments, each component 39, 40 andelements thereof may be customized to the anatomy of the subject.

TABLE 3 Dimension (mm) Metatarsal Base Member Length 22-26 Base MemberOuter Diameter Top  7-10 Base Member Outer Diameter Bottom 5-7Articulation Member Length 12-16 (Excluding Head Portion) ArticulationMember Outer Diameter Top 4-7 Articulation Member Outer Diameter Bottom3-5 Head Portion Diameter 10-13 Locking Member Outer Diameter 4-7Locking Member Inner Diameter 2-5 Locking Member Thickness 0.5 HeadPortion Height 2   Phalanx Base Member Length 18-22 Base Member OuterDiameter Top 10-13 Base Member Outer Diameter Bottom  7-10 ArticulationMember Length 10-15 (Excluding Head Portion) Articulation Member OuterDiameter Top  7-10 Articulation Member Outer Diameter Bottom 5-8 HeadPortion Diameter 10-13 Locking Member Outer Diameter  7-10 LockingMember Inner Diameter 5-8 Locking Member Thickness 0.5 Head PortionDepth 2  

As further illustrated in FIG. 6, the base member 41 of the metatarsalcomponent 39 is conical or tapered and has a generally circularcross-section. However, it is also contemplated that a base member 41may alternatively be non-conical or non-tapered, have another suitablecross-section, or combinations thereof, provided that other elements ofthe metatarsal component 39 are also adapted to fit such alternatives.For example, a base member 41 may have a cross-section selected fromgenerally elliptical, square, triangular, or other suitable shape. Thebase member 41 comprises a continuous first end 44, a non-continuoussecond end 45, and a cavity 46 for receiving a portion of the metatarsalarticulation member 42. The cavity 46 comprises a first end 47 recessedwithin the base member 41, a second end 48 that is partially shared withthe second end 45 of the base member 41, and a peripheral slot 49 forreceiving a portion of the locking member 43. As shown, the cavity 46 isgenerally conical or tapered and has a generally circular cross-section.However, it is also contemplated that the cavity 46 may alternatively benon-conical or non-tapered, have another suitable cross-section, orcombinations thereof, provided that other elements of the metatarsalcomponent 39 are also adapted to fit such alternatives. For example, acavity 46 may have a cross-section selected from generally elliptical,square, triangular, or other suitable shape. The slot 49 is integratedwith and formed around all or a portion of the cavity 46 in a directionaway from a longitudinal axis 50 of the base member 41. As shown, theslot 49 may be positioned at or proximate to the first end 47, but it isalso contemplated that it may alternatively be positioned elsewherealong the cavity 46, provided that the metatarsal articulation member 42is correspondingly adapted. Moreover, it is also contemplated that thefirst end 44 of the base member 41 may alternatively be non-continuousand partially shared with the first end 47 of the cavity 46.

The articulation member 42 of the metatarsal component 39 comprises ahead portion 51, a stem 54, and an integral slot 56. The head portion 51comprises a substantially convex bearing surface 52 and a proximalsurface 53 opposite thereto. As shown, the proximal surface 53 isgenerally planar, but it is also contemplated that it could benon-planar. The bearing surface 52 is adapted to emulate the generalshape and function of the head portion of the metatarsal bone within ametatarsophalangeal joint. The stem 54 protrudes from the center (notlabeled) of the proximal surface 53, terminates at a proximal end 55,and is adapted to be received within the cavity 46 of the base member41. When so received, the proximal surface 53 abuts the second end 45 ofthe base member 41. It is also contemplated that the proximal surface 53could be spaced from the second end 45 when so received. As shown, thestem 54 is generally conical or tapered and has a generally circularcross-section. However, it is also contemplated that the stem 54 mayalternatively be non-conical or non-tapered, have another suitablecross-section, or combinations thereof, provided that other elements ofthe metatarsal component 39 are also adapted to fit such alternatives.For example, a stem 54 may have a cross-section selected from generallyelliptical, square, triangular, or other suitable shape. The slot 56 isintegrated with and formed around all or a portion of the stem 54 in adirection towards a longitudinal axis 57 of the metatarsal articulationmember 42, and it is adapted to receive a portion of the locking member43. As shown, the slot 56 may be positioned at or proximate to theproximal end 55, but it is also contemplated that it may alternativelybe positioned elsewhere along the stem 54, provided that the base member41 is correspondingly adapted. The stem 54 and slot 56 are adapted tofit within the cavity 46 of the base member 41 such that both slots 49,56 are aligned to each receive a portion and together receive the wholeof the locking member 43.

The locking member 43 is a resilient spring member having at least afirst and a second configuration (not shown) and is adapted to bereceived within both slots 49, 56 to mechanically join the metatarsalarticulation member 42 with the base member 41. In some embodiments, themetatarsal articulation member 42 and the base member 41 are permanentlyjoined, and as such are effectively a single component of theimplantable device. As shown, the locking member 43 is non-continuousand has a generally circular cross-section. However, it is alsocontemplated that the locking member 43 may alternatively be continuous,have an different cross-section, or combinations thereof, provided thatother elements (including, but not limited to the slots 49, 56) of themetatarsal component 39 are correspondingly adapted. For example, alocking member 43 could have a cross-section selected from generallyelliptical, square, triangular, or other suitable cross-section. In someembodiments, the locking member 43 may comprise a resilient materialsuitable for surgical implants.

In some embodiments of assembly, the locking member 43 is flexed from afirst to a second configuration upon insertion through the partiallyshared second ends 45, 48 of the base member 41 and cavity 46; remainsin the second configuration as it is advanced along the cavity 46towards the first end 47; and upon encountering the slot 49 flexes fromthe second to the first configuration as it is received within the slot49. Alternatively, it is contemplated that the locking member 43 mayflex from the second to an intermediate third configuration as it isreceived within the slot 49.

In some embodiments of assembly, a portion of the locking member 43 isreceived within the slot 56 of the metatarsal articulating member 42;the stem 54 of said articulating member 42 is inserted through theshared ends 45, 48 of the base member 41 and cavity 46 as the lockingmember 43 flexes from a first to a second configuration; the lockingmember 43 remains in the second configuration as it and the stem 54 areadvanced along the cavity 46 towards the first end 47; and uponencountering the slot 49 of the base member 41, the locking member 43flexes from the second to the first configuration as it is receivedwithin the slot 49. Alternatively, it is contemplated that the lockingmember 43 may flex from the second to an intermediate thirdconfiguration as it is received within the slot 49.

A further illustrated in FIG. 7, the base member 44 of the phalanxcomponent 40 is conical or tapered and has a generally circularcross-section. However, it is also contemplated that a base member 44may alternatively be non-conical or non-tapered, have another suitablecross-section, or combinations thereof, provided that other elements ofthe phalanx component 40 are also adapted to fit such alternatives. Forexample, a base member 44 may have a cross-section selected fromgenerally elliptical, square, triangular, or other suitable shape. Thebase member 44 comprises a continuous first end 58, a non-continuoussecond end 59, and a cavity 60 for receiving a portion of the phalanxarticulation member 45. The cavity 60 comprises a first end 61 recessedwithin the base member 44, a second end 62 that is partially shared withthe second end 59 of the base member 44, and a peripheral slot 63 forreceiving a portion of the locking member 46. As shown, the cavity 60 isgenerally conical or tapered and has a generally circular cross-section.However, it is also contemplated that the cavity 60 may alternatively benon-conical or non-tapered, have another suitable cross-section, orcombinations thereof, provided that other elements of the phalanxcomponent 40 are also adapted to fit such alternatives. For example, acavity 60 may have a cross-section selected from generally elliptical,square, triangular, or other suitable shape. The slot 63 is integratedwith and formed around all or a portion of the cavity 60 in a directionaway from a longitudinal axis 64 of the base member 44. As shown, theslot 63 may be positioned at or proximate to the first end 61, but it isalso contemplated that it may alternatively be positioned elsewherealong the cavity 60, provided that the phalanx articulation member 45 iscorrespondingly adapted. Moreover, it is also contemplated that thefirst end 58 of the base member 44 may alternatively be non-continuousand partially shared with the first end 61 of the cavity 60.

The articulation member 45 of the phalanx component 40 comprises a headportion 65, a stem 68, and an integral slot 70. The head portion 65comprises a substantially concave bearing surface 66 and a distalsurface 67 opposite thereto. As shown, the distal surface 67 isgenerally planar, but it is also contemplated that it could benon-planar. The bearing surface 66 is adapted to emulate the generalshape and function of the proximal portion of the proximal phalanx bonewithin a metatarsophalangeal joint. The stem 68 protrudes from thecenter (not labeled) of the distal surface 67, terminates at a distalend 69, and is adapted to be received within the cavity 60 of the basemember 44. When so received, the distal surface 67 abuts the second end59 of the base member 44. It is also contemplated that the distalsurface 67 could be spaced from the second end 59 when so received. Asshown, the stem 68 is generally conical or tapered and has a generallycircular cross-section. However, it is also contemplated that the stem68 may alternatively be non-conical or non-tapered, have anothersuitable cross-section, or combinations thereof, provided that otherelements of the phalanx component 40 are also adapted to fit suchalternatives. For example, a stem 68 may have a cross-section selectedfrom generally elliptical, square, triangular, or other suitable shape.The slot 70 is integrated with and formed around all or a portion of thestem 68 in a direction towards a longitudinal axis 71 of the phalanxarticulation member 45, and it is adapted to receive a portion of thelocking member 46. As shown, the slot 70 may be positioned at orproximate to the distal end 69, but it is also contemplated that it mayalternatively be positioned elsewhere along the stem 68, provided thatthe base member 44 is correspondingly adapted. The stem 68 and slot 70are adapted to fit within the cavity 60 of the base member 44 such thatboth slots 63, 70 are aligned to each receive a portion and togetherreceive the whole of the locking member 46.

The locking member 46 is a resilient spring member having at least afirst and a second configuration (not shown) and is adapted to bereceived within both slots 63, 70 to mechanically join the phalanxarticulation member 45 with the base member 44. In some embodiments, thephalanx articulation member 45 and the base member 44 are permanentlyjoined, and as such are effectively a single component of theimplantable device. As shown, the locking member 46 is non-continuousand has a generally circular cross-section. However, it is alsocontemplated that the locking member 46 may alternatively be continuous,have an different cross-section, or combinations thereof, provided thatother elements (including, but not limited to the slots 63, 70) of thephalanx component 40 are correspondingly adapted. For example, a lockingmember 46 could have a cross-section selected from generally elliptical,square, triangular, or other suitable cross-section. In someembodiments, the locking member 46 may comprise a resilient materialsuitable for surgical implants.

In some embodiments of assembly, the locking member 46 is flexed from afirst to a second configuration upon insertion through the partiallyshared second ends 59, 62 of the base member 44 and cavity 60; remainsin the second configuration as it is advanced along the cavity 60towards the first end 61; and upon encountering the slot 63 flexes fromthe second to the first configuration as it is received within the slot63. Alternatively, it is contemplated that the locking member 46 mayflex from the second to an intermediate third configuration as it isreceived within the slot 63.

In some embodiments of assembly, a portion of the locking member 46 isreceived within the slot 70 of the phalanx articulating member 45; thestem 68 of said articulating member 45 is inserted through the sharedends 59, 62 of the base member 44 and cavity 60 as the locking member 46flexes from a first to a second configuration; the locking member 46remains in the second configuration as it and the stem 68 are advancedalong the cavity 60 towards the first end 61; and upon encountering theslot 63 of the base member 44, the locking member 46 flexes from thesecond to the first configuration as it is received within the slot 63.Alternatively, it is contemplated that the locking member 46 may flexfrom the second to an intermediate third configuration as it is receivedwithin the slot 63.

Referring to FIGS. 8-10, illustrated is another example of atwo-component implant 72 that comprises a metatarsal component 73 and aphalanx component 74. The metatarsal component 73 is designed to beimplanted into the distal end of a resected metatarsal bone to replaceall or a portion of the metatarsal head and function as the metatarsalcomponent of the metatarsophalangeal joint. The metatarsal component 73comprises a base member 75, a metatarsal articulation member 76, and alocking member 77. The base member 75 may be of any suitable length anddimension to allow for fixation within the metatarsal bone, and may befixed by any medically suitable means. In some embodiments, it isdesigned to be implanted in approximately one third of the length of themetatarsal bone. In some embodiments, the base member 75 is designed tobe fixed by tension on the interior cavity of the resected bone.

The phalanx component 74 is designed to be implanted into the proximalend of a resected proximal phalanx bone to replace all or a portion ofthe proximal end of the proximal phalanx and function as the phalanxcomponent of the metatarsophalangeal joint. The phalanx component 74comprises a base member 78, a phalanx articulation member 79, and alocking member 80. The base member 78 may be of any suitable length anddimension to allow for fixation within the phalanx bone, and may befixed by any medically suitable means. In some embodiments, it isdesigned to be implanted in approximately half of the length of thephalanx bone. In some embodiments, the base member 78 is designed to befixed by tension on the interior cavity of the resected bone.

In some embodiments, one or both of the metatarsal component 73 and thephalanx component 74 are implanted into the human foot to replace all ora portion of the metatarsophalangeal joint. In some embodiments, one orboth components 73, 74 may be implanted in a primary resectionalarthroplasty procedure, in a revision arthroplasty procedure performedto replace or compensate for a failed implant, or combinations thereof.In some embodiments, one or both components 73, 74 are implanted in arevision arthroplasty procedure. In some embodiments, each component 73,74 implanted may be selected from small, medium, or large sizes asnecessary to approximate the anatomy of the subject. In someembodiments, the components 73, 74 may comprise one or more dimensionsset forth in Table 3. In some embodiments, each component 73, 74 andelements thereof may be customized to the anatomy of the subject.

As further illustrated in FIG. 9, the base member 75 of the metatarsalcomponent 73 comprises primary 81 and secondary 82 body portions. Theprimary body portion 81 is conical or tapered and has a generallycircular cross-section. However, it is also contemplated that theprimary body portion 81 may alternatively be non-conical or non-tapered,have another suitable cross-section, or combinations thereof, providedthat other elements of the metatarsal component 73 are also adapted tofit such alternatives. For example, a primary body portion 81 may have across-section selected from generally elliptical, square, triangular, orother suitable shape. The secondary body portion 82 comprises one ormore flanges peripherally positioned around the primary body portion 81.As shown, the secondary body portion 82 comprises four flangesequidistantly positioned around the periphery of the primary bodyportion 81. Each of said flanges has a generally triangularcross-section, a length approximately two-thirds that of the primarybody portion 81, one end (not labeled) positioned at the second end 83of the base member 75, and runs longitudinally along the primary bodyportion 81. However, it is contemplated that the secondary body portion82 may have fewer or more flanges, that the flanges may have anothersuitable cross-section (for example, generally elliptical, square, orother suitable shape), that the flanges may have another suitablelength, that the flanges may be suitably spaced or positioned in adifferent manner, and combinations thereof. In some embodiments, thesecondary body portion 82 may be a resilient spring member adapted to bereceived within the interior cavity of a resected bone, wherein uponinsertion into the cavity, the secondary body portion 82 flexes from afirst to a second configuration (not shown) that exerts sufficienttension on the bone cavity to fix the base member 75. In someembodiments, the secondary body portion 82 may comprise a resilientmaterial suitable for surgical implants.

The base member 75 comprises a continuous first end 84, a non-continuoussecond end 83, and a cavity 85 for receiving a portion of the metatarsalarticulation member 76. The cavity 85 comprises a first end 86 recessedwithin the base member 75, a second end 87 that is partially shared withthe second end 83 of the base member 75, and a peripheral slot 88 forreceiving a portion of the locking member 77. As shown, the cavity 85 isgenerally conical or tapered and has a generally circular cross-section.However, it is also contemplated that the cavity 85 may alternatively benon-conical or non-tapered, have another suitable cross-section, orcombinations thereof, provided that other elements of the metatarsalcomponent 73 are also adapted to fit such alternatives. For example, acavity 85 may have a cross-section selected from generally elliptical,square, triangular, or other suitable shape. The slot 88 is integratedwith and formed around all or a portion of the cavity 85 in a directionaway from a longitudinal axis 89 of the base member 75. As shown, theslot 88 may be positioned at or proximate to the first end 86, but it isalso contemplated that it may alternatively be positioned elsewherealong the cavity 85, provided that the metatarsal articulation member 76is correspondingly adapted. Moreover, it is also contemplated that thefirst end 84 of the base member 75 may alternatively be non-continuousand partially shared with the first end 86 of the cavity 85.

The articulation member 76 of the metatarsal component 73 comprises ahead portion 90, a stem 93, and an integral slot 95. The head portion 90comprises a substantially convex bearing surface 91 and a proximalsurface 92 opposite thereto. As shown, the proximal surface 92 isgenerally planar, but it is also contemplated that it could benon-planar. The bearing surface 91 is adapted to emulate the generalshape and function of the head portion of the metatarsal bone within ametatarsophalangeal joint. The stem 93 protrudes from the center (notlabeled) of the proximal surface 92, terminates at a proximal end 94,and is adapted to be received within the cavity 85 of the base member75. When so received, the proximal surface 92 abuts the second end 83 ofthe base member 75. It is also contemplated that the proximal surface 92could be spaced from the second end 83 when so received. As shown, thestem 93 is generally conical or tapered and has a generally circularcross-section. However, it is also contemplated that the stem 93 mayalternatively be non-conical or non-tapered, have another suitablecross-section, or combinations thereof, provided that other elements ofthe metatarsal component 73 are also adapted to fit such alternatives.For example, a stem 93 may have a cross-section selected from generallyelliptical, square, triangular, or other suitable shape. The slot 95 isintegrated with and formed in a direction towards a longitudinal axis 96of the metatarsal articulation member 76 around all or a portion of thestem 93, and it is adapted to receive a portion of the locking member77. As shown, the slot 95 may be positioned at or proximate to theproximal end 94, but it is also contemplated that it may alternativelybe positioned elsewhere along the stem 93, provided that the base member75 is correspondingly adapted. The stem 93 and slot 95 are adapted tofit within the cavity 85 of the base member 75 such that both slots 88,95 are aligned to each receive a portion and together receive the wholeof the locking member 77.

The locking member 77 is a resilient spring member having at least afirst and a second configuration (not shown) and is adapted to bereceived within both slots 88, 95 to mechanically join the metatarsalarticulation member 76 with the base member 75. In some embodiments, themetatarsal articulation member 76 and the base member 75 are permanentlyjoined, and as such are effectively a single component of theimplantable device. As shown, the locking member 77 is non-continuousand has a generally circular cross-section. However, it is alsocontemplated that the locking member 77 may alternatively be continuous,have a different cross-section, or combinations thereof, provided thatother elements (including, but not limited to the slots 88, 95) of themetatarsal component 76 are correspondingly adapted. For example, alocking member 77 could have a cross-section selected from generallyelliptical, square, triangular, or other suitable cross-section. In someembodiments, the locking member 77 may comprise a resilient materialsuitable for surgical implants.

In some embodiments of assembly, the locking member 77 is flexed from afirst to a second configuration upon insertion through the partiallyshared second ends 83, 87 of the base member 75 and cavity 85; remainsin the second configuration as it is advanced along the cavity 85towards the first end 86; and upon encountering the slot 88 flexes fromthe second to the first configuration as it is received within the slot88. Alternatively, it is contemplated that the locking member 77 mayflex from the second to an intermediate third configuration as it isreceived within the slot 88.

In some embodiments of assembly, a portion of the locking member 77 isreceived within the slot 95 of the metatarsal articulating member 76;the stem 93 of said articulating member 76 is inserted through theshared ends 83, 87 of the base member 75 and cavity 85 as the lockingmember 77 flexes from a first to a second configuration; the lockingmember 77 remains in the second configuration as it and the stem 93 areadvanced along the cavity 85 towards the first end 86; and uponencountering the slot 88 of the base member 75, the locking member 77flexes from the second to the first configuration as it is receivedwithin the slot 88. Alternatively, it is contemplated that the lockingmember 77 may flex from the second to an intermediate thirdconfiguration as it is received within the slot 88.

As further illustrated in FIG. 10, the base member 78 of the phalanxcomponent 74 comprises primary 97 and secondary body 98 portions. Theprimary body portion 97 is conical or tapered and has a generallycircular cross-section. However, it is also contemplated that theprimary body portion 97 may alternatively be non-conical or non-tapered,have another suitable cross-section, or combinations thereof, providedthat other elements of the phalanx component 74 are also adapted to fitsuch alternatives. For example, a primary body portion 97 may have across-section selected from generally elliptical, square, triangular, orother suitable shape. The secondary body portion 98 comprises one ormore flanges peripherally positioned around the primary body portion 97.As shown, the secondary body portion 98 comprises four flangesequidistantly positioned around the periphery of the primary bodyportion 97. Each of said flanges has a generally triangularcross-section, a length approximately two-thirds that of the primarybody portion 97, one end (not labeled) positioned at the second end 99of the base member 78, and runs longitudinally along the primary bodyportion 97. However, it is contemplated that the secondary body portion98 may have fewer or more flanges, that the flanges may have anothersuitable cross-section (for example, generally elliptical, square, orother suitable shape), that the flanges may have another suitablelength, that the flanges may be suitably spaced or positioned in adifferent manner, and combinations thereof. In some embodiments, thesecondary body portion 98 may be a resilient spring member adapted to bereceived within the interior cavity of a resected bone, wherein uponinsertion into the cavity, the secondary body portion 98 flexes from afirst to a second configuration (not shown) that exerts sufficienttension on the bone cavity to fix the base member 78. In someembodiments, the secondary body portion 98 may comprise a resilientmaterial suitable for surgical implants.

The base member 78 comprises a continuous first end 100, anon-continuous second end 99, and a cavity 101 for receiving a portionof the phalanx articulation member 79. The cavity 101 comprises a firstend 102 recessed within the base member 78, a second end 103 that ispartially shared with the second end 99 of the base member 78, and aperipheral slot 104 for receiving a portion of the locking member 80. Asshown, the cavity 101 is generally conical or tapered and has agenerally circular cross-section. However, it is also contemplated thatthe cavity 101 may alternatively be non-conical or non-tapered, haveanother suitable cross-section, or combinations thereof, provided thatother elements of the phalanx component 74 are also adapted to fit suchalternatives. For example, a cavity 101 may have a cross-sectionselected from generally elliptical, square, triangular, or othersuitable shape. The slot 104 is integrated with and formed around all ora portion of the cavity 101 in a direction away from a longitudinal axis105 of the base member 78. As shown, the slot 104 may be positioned ator proximate to the first end 102, but it is also contemplated that itmay alternatively be positioned elsewhere along the cavity 101, providedthat the phalanx articulation member 79 is correspondingly adapted.Moreover, it is also contemplated that the first end 100 of the basemember 78 may alternatively be non-continuous and partially shared withthe first end 102 of the cavity 101.

The articulation member 79 of the phalanx component 74 comprises a headportion 106, a stem 109, and an integral slot 111. The head portion 106comprises a substantially concave bearing surface 107 and a distalsurface 108 opposite thereto. As shown, the distal surface 108 isgenerally planar, but it is also contemplated that it could benon-planar. The bearing surface 107 is adapted to emulate the generalshape and function of the proximal portion of the proximal phalanx bonewithin a metatarsophalangeal joint. The stem 109 protrudes from thecenter (not labeled) of the distal surface 108, terminates at a distalend 110, and is adapted to be received within the cavity 101 of the basemember 78. When so received, the distal surface 108 abuts the second end99 of the base member 78. It is also contemplated that the distalsurface 108 could be spaced from the second end 99 when so received. Asshown, the stem 109 is generally conical or tapered and has a generallycircular cross-section. However, it is also contemplated that the stem109 may alternatively be non-conical or non-tapered, have anothersuitable cross-section, or combinations thereof, provided that otherelements of the phalanx component 74 are also adapted to fit suchalternatives. For example, a stem 109 may have a cross-section selectedfrom generally elliptical, square, triangular, or other suitable shape.The slot 111 is integrated with and formed around all or a portion ofthe stem 109 in a direction towards a longitudinal axis 112 of thephalanx articulation member 79, and it is adapted to receive a portionof the locking member 80. As shown, the slot 111 may be positioned at orproximate to the distal end 110, but it is also contemplated that it mayalternatively be positioned elsewhere along the stem 109, provided thatthe base member 78 is correspondingly adapted. The stem 109 and slot 111are adapted to fit within the cavity 101 of the base member 78 such thatboth slots 104, 111 are aligned to each receive a portion and togetherreceive the whole of the locking member 80.

The locking member 80 is a resilient spring member having at least afirst and a second configuration (not shown) and is adapted to bereceived within both slots 104, 111 to mechanically join the phalanxarticulation member 79 with the base member 78. In some embodiments, thephalanx articulation member 79 and the base member 78 are permanentlyjoined, and as such are effectively a single component of theimplantable device. As shown, the locking member 80 is non-continuousand has a generally circular cross-section. However, it is alsocontemplated that the locking member 80 may alternatively be continuous,have an different cross-section, or combinations thereof, provided thatother elements (including, but not limited to the slots 104, 111) of thephalanx component 74 are correspondingly adapted. For example, a lockingmember 80 could have a cross-section selected from generally elliptical,square, triangular, or other suitable cross-section. In someembodiments, the locking member 80 may comprise a resilient materialsuitable for surgical implants.

In some embodiments of assembly, the locking member 80 is flexed from afirst to a second configuration upon insertion through the partiallyshared second ends 99, 103 of the base member 78 and cavity 101; remainsin the second configuration as it is advanced along the cavity 101towards the first end 102; and upon encountering the slot 104 flexesfrom the second to the first configuration as it is received within theslot 104. Alternatively, it is contemplated that the locking member 80may flex from the second to an intermediate third configuration as it isreceived within the slot 104.

In some embodiments of assembly, a portion of the locking member 80 isreceived within the slot 111 of the phalanx articulating member 79; thestem 109 of said articulating member 79 is inserted through the sharedends 99, 103 of the base member 78 and cavity 101 as the locking member80 flexes from a first to a second configuration; the locking member 80remains in the second configuration as it and the stem 109 are advancedalong the cavity 101 towards the first end 102; and upon encounteringthe slot 104 of the base member 78, the locking member 80 flexes fromthe second to the first configuration as it is received within the slot104. Alternatively, it is contemplated that the locking member 80 mayflex from the second to an intermediate third configuration as it isreceived within the slot 104.

Referring to FIGS. 11-19, illustrated are various examples ofimplantable devices of the invention which are designed to replace allor a portion of a metatarsophalangeal joint. Such devices comprise oneor more of: (i) a metatarsal component for surgical implantation intothe distal end of a metatarsal bone, comprising a metatarsalarticulation member comprising a substantially convex bearing surfaceand a locking member; and a base member adapted to be fixed within themetatarsal bone, the base member comprising a cavity adapted to receivethe locking member; wherein when the locking member is received by thecavity, the metatarsal articulation member is mechanically joined to thebase member; and (ii) a phalanx component for surgical implantation intothe proximal end of a proximal phalanx bone, comprising a phalanxarticulation member comprising a substantially concave bearing surfaceand a locking member; and a base member adapted to be fixed within thephalanx bone, the base member comprising a cavity adapted to receive thelocking member; wherein when the locking member is received by thecavity, the phalanx articulation member is mechanically joined to thebase member.

In those embodiment wherein one of the components is implanted, thechosen component is adapted to cooperatively engage with and move withrespect to either the proximal end of the proximal phalanx bone or thedistal end of the metatarsal bone. In those embodiments wherein both ofthe components are implanted, the metatarsal component and the phalanxcomponent are adapted to cooperatively engage such that the metatarsalarticulation member and the phalanx articulation member move withrespect to each other and collectively serve as a prostheticmetatarsophalangeal joint.

Referring to FIG. 11, illustrated is one example of a two-componentimplant device 113 comprising a metatarsal component 114 and a phalanxcomponent 115. The metatarsal component 114 is designed to be implantedinto the distal end of a resected metatarsal bone to replace all or aportion of the metatarsal head and function as the metatarsal componentof the metatarsophalangeal joint. The metatarsal component 114 comprisesa base member 116 and a metatarsal articulation member 117. The basemember 116 may be of any suitable length and dimension to allow forfixation within the metatarsal bone, and may be fixed by any medicallysuitable means. In some embodiments, the base member 116 is designed tobe implanted in approximately one third of the length of the metatarsalbone. In some embodiments, it is designed to be fixed by tension on theinterior cavity of the resected bone.

The phalanx component 115 is designed to be implanted into the proximalend of a resected proximal phalanx bone to replace all or a portion ofthe proximal end of the proximal phalanx and function as the phalanxcomponent of the metatarsophalangeal joint. The phalanx component 115comprises a base member 118 and a phalanx articulation member 119. Thebase member 118 may be of any suitable length and dimension to allow forfixation within the phalanx bone, and may be fixed by any medicallysuitable means. In some embodiments, the base member 118 is designed tobe implanted in approximately half of the length of the phalanx bone. Insome embodiments, it is designed to be fixed by tension on the interiorcavity of the resected bone.

In some embodiments, one or both of the metatarsal component 114 and thephalanx component 115 are implanted into the human foot to replace allor a portion of the metatarsophalangeal joint. In some embodiments, oneor both components 114, 115 may be implanted in a primary resectionalarthroplasty procedure, in a revision arthroplasty procedure performedto replace or compensate for a failed implant, or combinations thereof.In some embodiments, one or both components 114, 115 are implanted in arevision arthroplasty procedure. In some embodiments, each component114, 115 implanted may be selected from small, medium, or large sizes asnecessary to approximate the anatomy of the subject. In someembodiments, the components 114, 115 may comprise one or more dimensionsset forth in Table 4. In some embodiments, each component 114, 115 andelements thereof may be customized to the anatomy of the subject.

TABLE 4 Dimension (mm) Metatarsal Base Member Length 22-26 Base MemberOuter Diameter Top  7-10 Base Member Outer Diameter Bottom 5-7 CavityLength 5-7 Cavity Width 4-5 Slot Depression Diameter 4 Slot DepressionDepth   0.5 Head Portion Diameter 10-13 Head Portion Height 2 PhalanxBase Member Length 18-22 Base Member Outer Diameter Top 10-13 BaseMember Outer Diameter Bottom 6-7 Cavity Length  8-11 Cavity Width 4-5Slot Depression Diameter 5 Slot Depression Depth   0.5 Head PortionDiameter 10-13 Head Portion Depth 2

A further illustrated in FIG. 12, the base member 116 of the metatarsalcomponent 114 comprises primary 120 and secondary 121 body portions. Theprimary body portion 120 is conical or tapered and has a generallycircular cross-section. However, it is also contemplated that theprimary body portion 120 may alternatively be non-conical ornon-tapered, have another suitable cross-section, or combinationsthereof, provided that other elements of the metatarsal component 114are also adapted to fit such alternatives. For example, a primary bodyportion 120 may have a cross-section selected from generally elliptical,square, triangular, or other suitable shape. The secondary body portion121 comprises one or more flanges peripherally positioned around theprimary body portion 120. As shown, the secondary body portion 121comprises four flanges equidistantly positioned around the periphery ofthe primary body portion 120. Each of said flanges has a generallytriangular cross-section, a length approximately half that of theprimary body portion 120, one end (not labeled) positioned at the secondend 123 of the base member 116, and runs longitudinally along theprimary body portion 120. However, it is contemplated that the secondarybody portion 121 may have fewer or more flanges, that the flanges mayhave another suitable cross-section (for example, generally elliptical,square, or other suitable shape), that the flanges may have anothersuitable length, that the flanges may be suitably spaced or positionedin a different manner, and combinations thereof. In some embodiments,the secondary body portion 121 may be a resilient spring member adaptedto be received within the interior cavity of a resected bone, whereinupon insertion into the cavity, the secondary body portion 121 flexesfrom a first to a second configuration (not shown) that exertssufficient tension on the cavity to fix the base member 116. In someembodiments, the secondary body portion 121 may comprise a resilientmaterial suitable for surgical implants.

The base member 116 comprises a continuous first end 122, anon-continuous second end 123, and a cavity 124 for receiving a portionof the metatarsal articulation member 117. The cavity 124 comprises afirst end 125 recessed within the base member 116, a second end 126 thatis partially shared with the second end 123 of the base member 116, anda slot 127 for receiving a portion of a locking member 131. As shown,the cavity 124 has a generally rectangular cross-section. However, it isalso contemplated that the cavity 124 may alternatively have anothersuitable cross-section, provided that other elements of the metatarsalcomponent 114 are also adapted to fit such alternatives. For example, acavity 124 may have a cross-section selected from generally elliptical,square, or other suitable shape. As shown, the second end 126 of thecavity 124 is generally rectangular in shape. However, it is alsocontemplated that it may have another suitable shape, provided thatother elements of the metatarsal component 114 are also adapted to fitsuch alternatives. The slot 127 is integrated with the first end 125 andformed in a direction towards the first end 122 of the base member 116.As shown, the slot 127 may be positioned at or proximate to the center(not shown) of the first end 125, but it is also contemplated that itmay alternatively be positioned elsewhere on the first end 125, providedthat the metatarsal articulation member 117 is correspondingly adapted.

The articulation member 117 of the metatarsal component 114 comprises ahead portion 128 and a locking member 131. The head portion 128comprises a substantially convex bearing surface 129 and a proximalsurface 130 opposite thereto. As shown, the proximal surface 130 isgenerally planar, but it is also contemplated that it could benon-planar. The bearing surface 129 is adapted to emulate the generalshape and function of the head portion of the metatarsal bone within ametatarsophalangeal joint. The locking member 131 protrudes proximallyfrom the center (not labeled) of the proximal surface 130, terminates ata proximal end 132, and is adapted to be received within the cavity 124of the base member 116. When so received, the proximal surface 130 abutsthe second end 123 of the base member 116, and the proximal end 132 islocked within the slot 127.

The locking member 131 comprises a neck portion 133 abutting theproximal surface 130 of the metatarsal articulation member 117, a bodyportion 134 positioned between the neck portion 133 and the proximal end132, and the proximal end 132. As shown, each of the neck portion 133and body portion 134 has a generally rectangular cross-section, whereinthe rectangular cross-section of the neck portion 133 has at least oneof length, width, and height that is smaller than that of therectangular cross-section of the body portion 134. It is, however,contemplated that the neck portion 133 and body portion 134 of a lockingmember 131 may have another suitable cross-section, dimension, orcombination thereof, provided that other elements of the metatarsalcomponent 114 are also adapted to fit such alternatives. For example,the neck portion 133 and body portion 134 could alternatively have across-section selected from generally elliptical, circular, square, orother suitable shape.

As shown, the proximal end 132 has a generally circular cross-section.However, it is also contemplated that the proximal end 132 mayalternatively have another suitable cross-section, provided that otherelements of the metatarsal component 114 are also adapted to fit suchalternatives. For example, a proximal end 132 may have a cross-sectionselected from generally elliptical, square, triangular, or othersuitable shape. The proximal end 132 is adapted to fit within the slot127 of the cavity 124 of the base member 116.

In some embodiments, at least one of the locking member 131 and thesecond ends 123, 126 is suitably resilient such that the locking member131 may be received within the cavity 124 and the proximal end 132received within the slot 127 to mechanically join the metatarsalarticulation member 117 with the base member 116. In some embodiments,one or more of the locking member 131 and second ends 123, 126 maycomprise a resilient material suitable for surgical implants.

In some embodiments, the metatarsal articulation member 117 and the basemember 116 are permanently joined, and as such are effectively a singlecomponent of the implantable device. In some embodiments of assembly,the second ends 123, 126 may be flexed from a first to a secondconfiguration upon insertion of the locking member 131 into the cavity124; remain in the second configuration as the locking member 131 isadvanced within the cavity 124; and upon the proximal end 132encountering the slot 127 flexes from the second to the firstconfiguration as the proximal end 132 is received within the slot 127.Alternatively, it is contemplated that the second ends 123, 126 may flexfrom the second to an intermediate third configuration as the proximalend 132 is received within the slot 127.

As further illustrated in FIG. 13, the base member 118 of the phalanxcomponent 115 comprises primary 135 and secondary 136 body portions. Theprimary body portion 135 is conical or tapered and has a generallycircular cross-section. However, it is also contemplated that theprimary body portion 135 may alternatively be non-conical ornon-tapered, have another suitable cross-section, or combinationsthereof, provided that other elements of the phalanx component 115 arealso adapted to fit such alternatives. For example, a primary bodyportion 135 may have a cross-section selected from generally elliptical,square, triangular, or other suitable shape. The secondary body portion136 comprises one or more flanges peripherally positioned around theprimary body portion 135. As shown, the secondary body portion 136comprises four flanges equidistantly positioned around the periphery ofthe primary body portion 135. Each of said flanges has a generallytriangular cross-section, a length approximately half that of theprimary body portion 135, one end (not labeled) positioned at the secondend 138 of the base member 118, and runs longitudinally along theprimary body portion 135. However, it is contemplated that the secondarybody portion 136 may have fewer or more flanges, that the flanges mayhave another suitable cross-section (for example, generally elliptical,square, or other suitable shape), that the flanges may have anothersuitable length, that the flanges may be suitably spaced or positionedin a different manner, and combinations thereof. In some embodiments,the secondary body portion 136 may be a resilient spring member adaptedto be received within the interior cavity of a resected bone, whereinupon insertion into the cavity, the secondary body portion 136 flexesfrom a first to a second configuration (not shown) that exertssufficient tension on the bone cavity to fix the base member 118. Insome embodiments, the secondary body portion 136 may comprise aresilient material suitable for surgical implants.

The base member 118 comprises a continuous first end 137, anon-continuous second end 138, and a cavity 139 for receiving a portionof the phalanx articulation member 119. The cavity 139 comprises a firstend 140 recessed within the base member 118, a second end 141 that ispartially shared with the second end 138 of the base member 118, and aslot 142 for receiving a portion of a locking member 146. As shown, thecavity 139 has a generally rectangular cross-section. However, it isalso contemplated that the cavity 139 may alternatively have anothersuitable cross-section, provided that other elements of the phalanxcomponent 115 are also adapted to fit such alternatives. For example, acavity 139 may have a cross-section selected from generally elliptical,square, or other suitable shape. As shown, the second end 140 of thecavity 139 is generally rectangular in shape. However, it is alsocontemplated that it may have another suitable shape, provided thatother elements of the phalanx component 115 are also adapted to fit suchalternatives. The slot 142 is integrated with the first end 140 andformed in a direction towards the first end 137 of the base member 118.As shown, the slot 142 may be positioned at or proximate to the center(not shown) of the first end 140, but it is also contemplated that itmay alternatively be positioned elsewhere on the first end 140, providedthat the phalanx articulation member 119 is correspondingly adapted.

The articulation member 119 of the phalanx component 115 comprises ahead portion 143 and a locking member 146. The head portion 143comprises a substantially concave bearing surface 144 and a distalsurface 145 opposite thereto. As shown, the distal surface 145 isgenerally planar, but it is also contemplated that it could benon-planar. The bearing surface 144 is adapted to emulate the generalshape and function of the proximal portion of the proximal phalanx bonewithin a metatarsophalangeal joint. The locking member 146 protrudesdistally from the center (not labeled) of the distal surface 145,terminates at a distal end 147, and is adapted to be received within thecavity 139 of the base member 118. When so received, the distal surface145 abuts the second end 138 of the base member 118, and the distal end147 is locked within the slot 142.

The locking member 146 comprises a neck portion 148 abutting the distalsurface 145 of the phalanx articulation member 119, a body portion 149positioned between the neck portion 148 and the distal end 147, and thedistal end 147. As shown, each of the neck portion 148 and body portion149 has a generally rectangular cross-section, wherein the rectangularcross-section of the neck portion 148 has at least one of length, width,and height that is smaller than that of the rectangular cross-section ofthe body portion 149. It is, however, contemplated that the neck portion148 and body portion 149 of a locking member 146 may have anothersuitable cross-section, dimension, or combination thereof, provided thatother elements of the phalanx component 115 are also adapted to fit suchalternatives. For example, the neck portion 148 and body portion 149could alternatively have a cross-section selected from generallyelliptical, circular, square, or other suitable shape.

As shown, the distal end 147 has a generally circular cross-section.However, it is also contemplated that the distal end 147 mayalternatively have another suitable cross-section, provided that otherelements of the phalanx component 115 are also adapted to fit suchalternatives. For example, a distal end 147 may have a cross-sectionselected from generally elliptical, square, triangular, or othersuitable shape. The distal end 147 is adapted to fit within the slot 142of the cavity 139 of the base member 118.

In some embodiments, at least one of the locking member 146 and thesecond ends 138, 141 is suitably flexible such that the locking member146 may be received within the cavity 139 and the distal end 147received within the slot 142 to mechanically join the phalanxarticulation member 119 with the base member 118. In some embodiments,one or more of the locking member 146, and the second ends 138, 141 maycomprise a resilient material suitable for surgical implants.

In some embodiments, the phalanx articulation member 119 and the basemember 118 are permanently joined, and as such are effectively a singlecomponent of the implantable device. In some embodiments of operation,the second ends 138, 141 may be flexed from a first to a secondconfiguration upon insertion of the locking member 146 into the cavity139, remain in the second configuration as the locking member 146 isadvanced within the cavity 139, and upon the distal end 147 encounteringthe slot 142 flexes from the second to the first configuration as thedistal end 147 is received within the slot 142. Alternatively, it iscontemplated that the second ends 138, 141 may flex from the second toan intermediate third configuration as the distal end 147 is receivedwithin the slot 142.

Referring to FIGS. 14-16, illustrated is another example of atwo-component implant 150 comprising a metatarsal component 151 and aphalanx component 152. The metatarsal component 151 is designed to beimplanted into the distal end of a resected metatarsal bone to replaceall or a portion of the metatarsal head and function as the metatarsalcomponent of the metatarsophalangeal joint. The metatarsal component 151comprises a base member 153 and a metatarsal articulation member 154.The base member 153 may be of any suitable length and dimension to allowfor fixation within the metatarsal bone, and may be fixed by anymedically suitable means. In some embodiments, the base member 153 isdesigned to be implanted in approximately one third of the length of themetatarsal bone. In some embodiments, it may be fixed with bone cement.

The phalanx component 152 is designed to be implanted into the proximalend of a resected proximal phalanx bone to replace all or a portion ofthe proximal end of the proximal phalanx and function as the phalanxcomponent of the metatarsophalangeal joint. The phalanx component 152comprises a base member 155 and a phalanx articulation member 156. Thebase member 155 may be of any suitable length and dimension to allow forfixation within the phalanx bone, and may be fixed by any medicallysuitable means. In some embodiments, the base member 155 is designed tobe implanted in approximately half of the length of the phalanx bone. Insome embodiments, it may be fixed with bone cement.

In some embodiments, one or both of the metatarsal component 151 and thephalanx component 152 are implanted into the human foot to replace allor a portion of the metatarsophalangeal joint. In some embodiments, oneor both components 151, 152 may be implanted in a primary resectionalarthroplasty procedure, in a revision arthroplasty procedure performedto replace or compensate for a failed implant, or combinations thereof.In some embodiments, one or both components 151, 152 are implanted in aprimary resectional arthroplasty procedure. In some embodiments, eachcomponent 151, 152 implanted may be selected from small, medium, orlarge sizes as necessary to approximate the anatomy of the subject. Insome embodiments, the components 151, 152 may comprise one or moredimensions set forth in Table 5. In some embodiments, each component151, 152 and elements thereof may be customized to the anatomy of thesubject.

TABLE 5 Dimension (mm) Metatarsal Base Member Length 22-26 Base MemberOuter Diameter Top  7-10 Base Member Outer Diameter Bottom  7-10 CavityLength 5-8 Cavity Width 4-5 Slot Depression Diameter 5 Slot DepressionDepth   0.5 Head Portion Diameter 10-13 Head Portion Height 2 PhalanxBase Member Length 18-22 Base Member Outer Diameter Top 10-13 BaseMember Outer Diameter Bottom 10-13 Cavity Length  8-11 Cavity Width 4-5Slot Depression Diameter 5 Slot Depression Depth   0.5 Head PortionDiameter 10-13 Head Portion Depth 2

A further illustrated in FIG. 15, the base member 153 of the metatarsalcomponent 151 is cylindrical and has a generally circular cross-section.However, it is also contemplated that the base member 153 mayalternatively be non-cylindrical, have another suitable cross-section,or combinations thereof, provided that other elements of the metatarsalcomponent 151 are also adapted to fit such alternatives. For example, abase member 153 may have a cross-section selected from generallyelliptical, square, triangular, or other suitable shape. The base member153 comprises a continuous first end 157, a non-continuous second end158, and a cavity 159 for receiving a portion of the metatarsalarticulation member 154. The cavity 159 comprises a first end 160recessed within the base member 153, a second end 161 that is partiallyshared with the second end 158 of the base member 153, and a slot 162for receiving a portion of a locking member 166. As shown, the cavity159 has a generally rectangular cross-section. However, it is alsocontemplated that the cavity 159 may alternatively have another suitablecross-section, provided that other elements of the metatarsal component151 are also adapted to fit such alternatives. For example, a cavity 159may have a cross-section selected from generally elliptical, square, orother suitable shape.

As shown, the second end 160 of the cavity 159 is generally rectangularin shape. However, it is also contemplated that it may have anothersuitable shape, provided that other elements of the metatarsal component151 are also adapted to fit such alternatives. The slot 162 isintegrated with the first end 160 and formed in a direction towards thefirst end 157 of the base member 153. As shown, the slot 162 may bepositioned at or proximate to the center (not shown) of the first end160, but it is also contemplated that it may alternatively be positionedelsewhere on the first end 160, provided that the metatarsalarticulation member 154 is correspondingly adapted.

The articulation member 154 of the metatarsal component 151 comprises ahead portion 163 and a locking member 166. The head portion 163comprises a substantially convex bearing surface 164 and a proximalsurface 165 opposite thereto. As shown, the proximal surface 165 isgenerally planar, but it is also contemplated that it could benon-planar. The bearing surface 164 is adapted to emulate the generalshape and function of the head portion of the metatarsal bone within ametatarsophalangeal joint. The locking member 166 protrudes proximallyfrom the center (not labeled) of the proximal surface 165, terminates ata proximal end 167, and is adapted to be received within the cavity 159of the base member 153. When so received, the proximal surface 165 abutsthe second end 158 of the base member 153, and the proximal end 167 islocked within the slot 162.

The locking member 166 comprises a neck portion 168 abutting theproximal surface 165 of the metatarsal articulation member 154, a bodyportion 169 positioned between the neck portion 168 and the proximal end167, and the proximal end 167. As shown, each of the neck portion 168and body portion 169 has a generally rectangular cross-section, whereinthe rectangular cross-section of the neck portion 168 has at least oneof length, width, and height that is smaller than that of therectangular cross-section of the body portion 169. It is, however,contemplated that the neck portion 168 and body portion 169 of a lockingmember 166 may have another suitable cross-section, dimension, orcombination thereof, provided that other elements of the metatarsalcomponent 151 are also adapted to fit such alternatives. For example,the neck portion 168 and body portion 169 could alternatively have across-section selected from generally elliptical, circular, square, orother suitable shape.

As shown, the proximal end 167 has a generally circular cross-section.However, it is also contemplated that the proximal end 167 mayalternatively have another suitable cross-section, provided that otherelements of the metatarsal component 151 are also adapted to fit suchalternatives. For example, a proximal end 167 may have a cross-sectionselected from generally elliptical, square, triangular, or othersuitable shape. The proximal end 167 is adapted to fit within the slot162 of the cavity 159 of the base member 153.

In some embodiments, at least one of the locking member 166 and thesecond ends 158, 161 is suitably flexible such that the locking member166 may be received within the cavity 159 and the proximal end 167received within the slot 162 to mechanically join the metatarsalarticulation member 154 with the base member 153. In some embodiments,one or more of the locking member 166 and the second ends 158, 161 maycomprise a resilient material suitable for surgical implants. In someembodiments, the metatarsal articulation member 154 and the base member153 are permanently joined, and as such are effectively a singlecomponent of the implantable device. In some embodiments of assembly,the second ends 158, 161 may be flexed from a first to a secondconfiguration upon insertion of the locking member 166 into the cavity159; remain in the second configuration as the locking member 166 isadvanced within the cavity 159; and upon the proximal end 167encountering the slot 162 flexes from the second to the firstconfiguration as the proximal end 167 is received within the slot 162.Alternatively, it is contemplated that the second ends 158, 161 may flexfrom the second to an intermediate third configuration as the proximalend 167 is received within the slot 162.

A further illustrated in FIG. 16, the base member 155 of the phalanxcomponent 152 is cylindrical and has a generally circular cross-section.However, it is also contemplated that the base member 155 mayalternatively be non-cylindrical, have another suitable cross-section,or combinations thereof, provided that other elements of the phalanxcomponent 152 are also adapted to fit such alternatives. For example, abase member 155 may have a cross-section selected from generallyelliptical, square, triangular, or other suitable shape. The base member155 comprises a continuous first end 170, a non-continuous second end171, and a cavity 172 for receiving a portion of the phalanxarticulation member 156. The cavity 172 comprises a first end 173recessed within the base member 155, a second end 174 that is partiallyshared with the second end 171 of the base member 155, and a slot 175for receiving a portion of a locking member 179. As shown, the cavity172 has a generally rectangular cross-section. However, it is alsocontemplated that the cavity 172 may alternatively have another suitablecross-section, provided that other elements of the phalanx component 152are also adapted to fit such alternatives. For example, a cavity 172 mayhave a cross-section selected from generally elliptical, square, orother suitable shape. As shown, the second end 174 of the cavity 172 isgenerally rectangular in shape. However, it is also contemplated that itmay have another suitable shape, provided that other elements of thephalanx component 152 are also adapted to fit such alternatives. Theslot 175 is integrated with the first end 173 and formed in a directiontowards the first end 170 of the base member 155. As shown, the slot 175may be positioned at or proximate to the center (not shown) of the firstend 173, but it is also contemplated that it may alternatively bepositioned elsewhere on the first end 173, provided that the phalanxarticulation member 156 is correspondingly adapted.

The articulation member 156 of the phalanx component 152 comprises ahead portion 176 and a locking member 179. The head portion 176comprises a substantially concave bearing surface 177 and a distalsurface 178 opposite thereto. As shown, the distal surface 178 isgenerally planar, but it is also contemplated that it could benon-planar. The bearing surface 177 is adapted to emulate the generalshape and function of the proximal portion of the proximal phalanx bonewithin a metatarsophalangeal joint. The locking member 179 protrudesdistally from the center (not labeled) of the distal surface 178,terminates at a distal end 180, and is adapted to be received within thecavity 172 of the base member 155. When so received, the distal surface178 abuts the second end 171 of the base member 155, and the distal end180 is locked within the slot 175.

The locking member 179 comprises a neck portion 181 abutting the distalsurface 178 of the phalanx articulation member 156, a body portion 182positioned between the neck portion 181 and the distal end 180, and thedistal end 180. As shown, each of the neck portion 181 and body portion182 has a generally rectangular cross-section, wherein the rectangularcross-section of the neck portion 181 has at least one of length, width,and height that is smaller than that of the rectangular cross-section ofthe body portion 182. It is, however, contemplated that the neck portion181 and body portion 182 of a locking member 179 may have anothersuitable cross-section, dimension, or combination thereof, provided thatother elements of the phalanx component 152 are also adapted to fit suchalternatives. For example, the neck portion 181 and body portion 182could alternatively have a cross-section selected from generallyelliptical, circular, square, or other suitable shape.

As shown, the distal end 180 has a generally circular cross-section.However, it is also contemplated that the distal end 180 mayalternatively have another suitable cross-section, provided that otherelements of the phalanx component 152 are also adapted to fit suchalternatives. For example, a distal end 180 may have a cross-sectionselected from generally elliptical, square, triangular, or othersuitable shape. The distal end 180 is adapted to fit within the slot 175of the cavity 172 of the base member 155.

In some embodiments, at least one of the locking member 179 and thesecond ends 171, 174 is suitably flexible such that the locking member179 may be received within the cavity 172 and the distal end 180received within the slot 172 to mechanically join the phalanxarticulation member 156 with the base member 155. In some embodiments,one or more of the locking member 179 and the second ends 171, 174 maycomprise a resilient material suitable for surgical implants. In someembodiments, the phalanx articulation member 156 and the base member 155are permanently joined, and as such are effectively a single componentof the implantable device. In some embodiments of assembly, the secondends 171, 174 may be flexed from a first to a second configuration uponinsertion of the locking member 179 into the cavity 172; remain in thesecond configuration as the locking member 179 is advanced within thecavity 172; and upon the distal end 180 encountering the slot 175 flexesfrom the second to the first configuration as the distal end 180 isreceived within the slot 175. Alternatively, it is contemplated that thesecond ends 171, 174 may flex from the second to an intermediate thirdconfiguration as the distal end 180 is received within the slot 175.

Referring to FIGS. 17-19, illustrated is another example of atwo-component device 183 comprising a metatarsal component 184 and aphalanx component 185. The metatarsal component 184 is designed to beimplanted into the distal end of a resected metatarsal bone to replaceall or a portion of the metatarsal head and function as the metatarsalcomponent of the metatarsophalangeal joint. The metatarsal component 184comprises a base member 186 and a metatarsal articulation member 187.The base member 186 may be of any suitable length and dimension to allowfor fixation within the metatarsal bone, and may be fixed by anymedically suitable means. In some embodiments, the base member 186 isdesigned to be implanted in approximately one third of the length of themetatarsal bone. In some embodiments, it may be fixed with bone cement.

The phalanx component 185 is designed to be implanted into the proximalend of a resected proximal phalanx bone to replace all or a portion ofthe proximal end of the proximal phalanx and function as the phalanxcomponent of the metatarsophalangeal joint. The phalanx component 185comprises a base member 188 and a phalanx articulation member 189. Thebase member 188 may be of any suitable length and dimension to allow forfixation within the phalanx bone, and may be fixed by any medicallysuitable means. In some embodiments, the base member 188 is designed tobe implanted in approximately half of the length of the phalanx bone. Insome embodiments, it may be fixed with bone cement.

In some embodiments, one or both of the metatarsal component 184 and thephalanx component 185 are implanted into the human foot to replace allor a portion of the metatarsophalangeal joint. In some embodiments, oneor both components 184, 185 may be implanted in a primary resectionalarthroplasty procedure, in a revision arthroplasty procedure performedto replace or compensate for a failed implant, or combinations thereof.In some embodiments, one or both components 184, 185 are implanted in arevision arthroplasty procedure. In some embodiments, each component184, 185 implanted may be selected from small, medium, or large sizes asnecessary to approximate the anatomy of the subject. In someembodiments, the components 184, 185 may comprise one or more dimensionsset forth in Table 4. In some embodiments, each component 184, 185 andelements thereof may be customized to the anatomy of the subject.

A further illustrated in FIG. 18, the base member 186 of the metatarsalcomponent 184 is conical or tapered and has a generally circularcross-section. However, it is also contemplated that the base member 186may alternatively be non-conical or non-tapered, have another suitablecross-section, or combinations thereof, provided that other elements ofthe metatarsal component 184 are also adapted to fit such alternatives.For example, a base member 186 may have a cross-section selected fromgenerally elliptical, square, triangular, or other suitable shape. Thebase member 186 comprises a continuous first end 190, a non-continuoussecond end 191, and a cavity 192 for receiving a portion of themetatarsal articulation member 187. The cavity 192 comprises a first end193 recessed within the base member 186, a second end 194 that ispartially shared with the second end 191 of the base member 186, and aslot 195 for receiving a portion of a locking member 199. As shown, thecavity 192 has a generally rectangular cross-section. However, it isalso contemplated that the cavity 192 may alternatively have anothersuitable cross-section, provided that other elements of the metatarsalcomponent 184 are also adapted to fit such alternatives. For example, acavity 192 may have a cross-section selected from generally elliptical,square, or other suitable shape.

As shown, the second end 194 of the cavity 192 is generally rectangularin shape. However, it is also contemplated that it may have anothersuitable shape, provided that other elements of the metatarsal component184 are also adapted to fit such alternatives. The slot 195 isintegrated with the first end 193 and formed in a direction towards thefirst end 190 of the base member 186. As shown, the slot 195 may bepositioned at or proximate to the center (not shown) of the first end193, but it is also contemplated that it may alternatively be positionedelsewhere on the first end 193, provided that the metatarsalarticulation member 187 is correspondingly adapted.

The articulation member 187 of the metatarsal component 184 comprises ahead portion 196 and a locking member 199. The head portion 196comprises a substantially convex bearing surface 197 and a proximalsurface 198 opposite thereto. As shown, the proximal surface 198 isgenerally planar, but it is also contemplated that it could benon-planar. The bearing surface 197 is adapted to emulate the generalshape and function of the head portion of the metatarsal bone within ametatarsophalangeal joint. The locking member 199 protrudes proximallyfrom the center (not labeled) of the proximal surface 198, terminates ata proximal end 200, and is adapted to be received within the cavity 192of the base member 186. When so received, the proximal surface 198 abutsthe second end 191 of the base member 186, and the proximal end 200 islocked within the slot 195.

The locking member 199 comprises a neck portion 201 abutting theproximal surface 198 of the metatarsal articulation member 187, a bodyportion 202 positioned between the neck portion 201 and the proximal end200, and the proximal end 200. As shown, each of the neck portion 201and body portion 202 has a generally rectangular cross-section, whereinthe rectangular cross-section of the neck portion 201 has at least oneof length, width, and height that is smaller than that of therectangular cross-section of the body portion 202. It is, however,contemplated that the neck portion 201 and body portion 202 of a lockingmember 199 may have another suitable cross-section, dimension, orcombination thereof, provided that other elements of the metatarsalcomponent 184 are also adapted to fit such alternatives. For example,the neck portion 201 and body portion 202 could alternatively have across-section selected from generally elliptical, circular, square, orother suitable shape.

As shown, the proximal end 200 has a generally circular cross-section.However, it is also contemplated that the proximal end 200 mayalternatively have another suitable cross-section, provided that otherelements of the metatarsal component 184 are also adapted to fit suchalternatives. For example, a proximal end 200 may have a cross-sectionselected from generally elliptical, square, triangular, or othersuitable shape. The proximal end 200 is adapted to fit within the slot195 of the cavity 192 of the base member 186.

In some embodiments, at least one of the locking member 199 and thesecond ends 191, 194 is suitably flexible such that the locking member199 may be received within the cavity 192 and the proximal end 200received within the slot 195 to mechanically join the metatarsalarticulation member 187 with the base member 186. In some embodiments,one or more of the locking member 199 and the second ends 191, 194 maycomprise a resilient material suitable for surgical implants. In someembodiments, the metatarsal articulation member 187 and the base member186 are permanently joined, and as such are effectively a singlecomponent of the implantable device. In some embodiments of assembly,the second ends 191, 194 may be flexed from a first to a secondconfiguration upon insertion of the locking member 199 into the cavity192; remain in the second configuration as the locking member 199 isadvanced within the cavity 192; and upon the proximal end 200encountering the slot 195 flexes from the second to the firstconfiguration as the proximal end 200 is received within the slot 195.Alternatively, it is contemplated that the second ends 191, 194 may flexfrom the second to an intermediate third configuration as the proximalend 200 is received within the slot 195.

A further illustrated in FIG. 19, the base member 188 of the phalanxcomponent 185 is conical or tapered and has a generally circularcross-section. However, it is also contemplated that the base member 188may alternatively be non-conical or non-tapered, have another suitablecross-section, or combinations thereof, provided that other elements ofthe phalanx component 185 are also adapted to fit such alternatives. Forexample, a base member 188 may have a cross-section selected fromgenerally elliptical, square, triangular, or other suitable shape. Thebase member 188 comprises a continuous first end 203, a non-continuoussecond end 204, and a cavity 205 for receiving a portion of the phalanxarticulation member 189. The cavity 205 comprises a first end 206recessed within the base member 188, a second end 207 that is partiallyshared with the second end 204 of the base member 188, and a slot 208for receiving a portion of a locking member 212. As shown, the cavity205 has a generally rectangular cross-section. However, it is alsocontemplated that the cavity 205 may alternatively have another suitablecross-section, provided that other elements of the phalanx component 185are also adapted to fit such alternatives. For example, a cavity 205 mayhave a cross-section selected from generally elliptical, square, orother suitable shape. As shown, the second end 207 of the cavity 205 isgenerally rectangular in shape. However, it is also contemplated that itmay have another suitable shape, provided that other elements of thephalanx component 185 are also adapted to fit such alternatives. Theslot 208 is integrated with the first end 206 and formed in a directiontowards the first end 203 of the base member 188. As shown, the slot 208may be positioned at or proximate to the center (not shown) of the firstend 206, but it is also contemplated that it may alternatively bepositioned elsewhere on the first end 206, provided that the phalanxarticulation member 189 is correspondingly adapted.

The articulation member 189 of the phalanx component 185 comprises ahead portion 209 and a locking member 212. The head portion 209comprises a substantially concave bearing surface 210 and a distalsurface 211 opposite thereto. As shown, the distal surface 211 isgenerally planar, but it is also contemplated that it could benon-planar. The bearing surface 210 is adapted to emulate the generalshape and function of the proximal portion of the proximal phalanx bonewithin a metatarsophalangeal joint. The locking member 212 protrudesdistally from the center (not labeled) of the distal surface 211,terminates at a distal end 213, and is adapted to be received within thecavity 205 of the base member 188. When so received, the distal surface211 abuts the second end 204 of the base member 188, and the distal end213 is locked within the slot 208.

The locking member 212 comprises a neck portion 214 abutting the distalsurface 211 of the phalanx articulation member 189, a body portion 215positioned between the neck portion 214 and the distal end 213, and thedistal end 213. As shown, each of the neck portion 214 and body portion215 has a generally rectangular cross-section, wherein the rectangularcross-section of the neck portion 214 has at least one of length, width,and height that is smaller than that of the rectangular cross-section ofthe body portion 215. It is, however, contemplated that the neck portion214 and body portion 215 of a locking member 212 may have anothersuitable cross-section, dimension, or combination thereof, provided thatother elements of the phalanx component 185 are also adapted to fit suchalternatives. For example, the neck portion 214 and body portion 215could alternatively have a cross-section selected from generallyelliptical, circular, square, or other suitable shape.

As shown, the distal end 213 has a generally circular cross-section.However, it is also contemplated that the distal end 213 mayalternatively have another suitable cross-section, provided that otherelements of the phalanx component 185 are also adapted to fit suchalternatives. For example, a distal end 213 may have a cross-sectionselected from generally elliptical, square, triangular, or othersuitable shape. The distal end 213 is adapted to fit within the slot 208of the cavity 205 of the base member 188.

In some embodiments, at least one of the locking member 212 and thesecond ends 204, 207 is suitably flexible such that the locking member212 may be received within the cavity 205 and the distal end 213received within the slot 208 to mechanically join the phalanxarticulation member 189 with the base member 188. In some embodiments,one or more of the locking member 212 and the second ends 204, 207 maycomprise a resilient material suitable for surgical implants. In someembodiments, the phalanx articulation member 189 and the base member 188are permanently joined, and as such are effectively a single componentof the implantable device. In some embodiments of operation, the secondends 204, 207 may be flexed from a first to a second configuration uponinsertion of the locking member 212 into the cavity 205; remain in thesecond configuration as the locking member 212 is advanced within thecavity 205; and upon the distal end 213 encountering the slot 208 flexesfrom the second to the first configuration as the distal end 213 isreceived within the slot 208. Alternatively, it is contemplated that thesecond ends 204, 207 may flex from the second to an intermediate thirdconfiguration as the distal end 213 is received within the slot 208.

Referring to FIGS. 20-25, illustrated are various examples ofimplantable devices of the invention which are designed to replace allor a portion of a metatarsophalangeal joint. Such devices comprise oneor more of: (i) a metatarsal component for surgical implantation intothe distal end of a metatarsal bone, comprising a metatarsalarticulation member comprising a substantially convex bearing surfaceand a cavity adapted to receive at least a portion of a locking member;a base member adapted to be fixed within the metatarsal bone; a lockingmember adapted to be at least partially received by the cavity; whereinwhen the locking member is received within the cavity, the metatarsalarticulation member is mechanically joined to the base member; and (ii)a phalanx component for surgical implantation into the proximal end of aproximal phalanx bone, comprising a phalanx articulation membercomprising a substantially convex bearing surface and a cavity adaptedto receive at least a portion of a locking member; a base member adaptedto be fixed within the phalanx bone; a locking member adapted to be atleast partially received by the cavity; wherein when the locking memberis received within the cavity, the phalanx articulation member ismechanically joined to the base member.

In those embodiments wherein one of the components is implanted, thechosen component is adapted to cooperatively engage with and move withrespect to either the proximal end of the proximal phalanx bone or thedistal end of the metatarsal bone. In those embodiments wherein both ofthe components are implanted, the metatarsal component and the phalanxcomponent are adapted to cooperatively engage such that the metatarsalarticulation member and the phalanx articulation member move withrespect to each other and collectively serve as a prostheticmetatarsophalangeal joint.

Referring to FIG. 20, illustrated is one example of a device comprisinga metatarsal articulation member 216, a phalanx articulation member 217,a base member 218, and a screw member 219. The base member 218 isdesigned to be implanted into the distal end of a resected metatarsalbone, the proximal end of a resected proximal phalanx bone, or both. Thebase member 218 may be of any suitable length and dimension to allow forfixation within the metatarsal and phalanx bones, and may be fixed byany medically suitable means. In some embodiments, the base member 218is designed to be implanted in approximately one third of the length ofthe metatarsal bone or half of the length of the phalanx bone. In someembodiments, it is designed to be fixed by tension on the interiorcavity of the resected bone. When the metatarsal-implanted base member218 is mechanically joined to the metatarsal articulation member 216,the device is designed to replace all or a portion of the metatarsalhead and function as the metatarsal component of the metatarsophalangealjoint. When the phalanx-implanted base member 218 is mechanically joinedto the phalanx articulation member 217, the device is designed toreplace all or a portion of the proximal end of the proximal phalanx andfunction as the phalanx component of the metatarsophalangeal joint.

In some embodiments, the device may be implanted into one or both of themetatarsal and phalanx bones in a primary resectional arthroplastyprocedure, in a revision arthroplasty procedure performed to replace orcompensate for a failed implant, or combinations thereof. In someembodiments, implantation is by a revision arthroplasty procedure. Insome embodiments, each device implanted may be selected from small,medium, or large sizes as necessary to approximate the anatomy of thesubject. In some embodiments, the devices may comprise one or moredimensions set forth in Table 6. In some embodiments, each device andelements thereof may be customized to the anatomy of the subject.

TABLE 6 Dimension Metatarsal and Phalanx (mm) Base Member LengthMetatarsal 22-26 Base Member Length Phalange 18-22 Base Member HeadPortion Height 5-6 Base Member Head Portion Without Flange  9-10 BaseMember Head Portion and Flange Width 10-11 Screw Length Metatarsal 22-26Screw Length Phalange 18-22 Screw Head Height 2 Screw Head Diameter 9-10 Articulation Member Height 10  (Excluding Bearing Surface)Articulation Member Bearing Surface 16-22 Diameter Bearing Surface Depth2 Bearing Surface Height 2

A further illustrated in FIG. 21, the base member 218 comprises a firstend 220, a second end 221 comprising a head portion 222, a body portion223, and a cavity 224 for receiving the screw member 219. As shown, thefirst 220 and second 221 ends are non-continuous. The cavity 224 iscontinuous through the base member 218 from the first end 220 to thesecond end 221. As shown, the cavity 224 and body portion 223 areconical or tapered and have a generally non-continuous cross-sectionwith a generally circular shape. It is, however, contemplated that thecavity 224 and body portion 223 could alternatively be non-conical ornon-tapered, have another suitable cross-section, or combinationsthereof, provided that other elements of the device are also adapted tofit such alternatives. For example, a cross-section could be selectedfrom generally elliptical, square, or other suitable shape. In someembodiments, the body portion 223 may be a resilient member adapted tobe received within the interior cavity of a resected bone, wherein thebody portion 223 expands in response to the screw member 219 beingreceived and advanced within the cavity 224 and exerts sufficienttension on the bone cavity to fix the base member 218 therein. In someembodiments, the body portion 223 may comprise a resilient materialsuitable for surgical implants.

The head portion 222 has a generally rectangular cross-section. However,it is also contemplated that a head portion 222 could alternatively haveanother suitable cross-section, provided that other elements of thedevice are also adapted to fit such alternatives. For example, a headportion 222 could have a cross-section selected from generallyelliptical, square, or other suitable shape. The head portion 222comprises a locking member 225. In some embodiments, the locking member225 comprises a pair of flanges, each opposably positioned on theexterior of the head portion 222. As shown, the flanges are positionedat or proximate to the body portion 223, are perpendicular to alongitudinal axis 226, and have a generally rectangular cross-sectionwith at least one of length, width, or height that is the same as thatof the cross-section of the head portion 222. It is also contemplatedthat the head portion 222 could comprise a locking member 225 with morethan one pair of flanges, that the flanges could be alternativelypositioned, that the flanges could have a different cross-section ordimension, or combinations thereof, provided that other elements of thedevice are also adapted to fit such alternatives. In some embodiments,the flanges are a locking member 225 adapted to mechanically join themetatarsal articulation member 216 or the phalanx articulation member217 to the base member 218. The head portion 222 further comprises aninterior (female) screw thread 227 along the portion of the cavity 224formed within the head portion 222, said screw thread 227 adapted toreceive a portion of the screw member 219.

As shown, the screw member 219 comprises a first end 228, a second end229 comprising a head portion 230, and a body portion 231 comprising anexternal (male) screw thread 232. The screw thread 232 is adapted to beat least partially received by the interior screw thread 227 of the basemember 218. The screw member 219 is generally cylindrical and has agenerally circular cross-section. However, it is also contemplated thatthe screw member 219 could alternatively be non-cylindrical, have andifferent cross-section, or combinations thereof, provided that otherelements of the device are correspondingly adapted. For example, a screwmember 219 could be tapered or conical or have a helical cross-section.The head portion 230 of the screw member 219 has a cross-section largerthan that of the body portion 231. Additionally, the head portion 230comprises a slot 233 centrally positioned on the second end 229. Asshown, the slot 233 has a generally rectangular cross-section. However,it is also contemplated that the slot 233 could alternatively haveanother suitable cross-section. The screw member 219 is adapted to bereceived within the cavity 224 of the base member 218. When the screwmember 219 is so received, the head portion 230 abuts the second end 221of the base member 218. When so received, the combination of the screwmember 219 and base member 218 is adapted be at least partially receivedby the metatarsal articulation member 216, the phalanx articulationmember 217, or both and mechanically joined by the locking member 225.

As further illustrated in FIG. 22, the metatarsal articulation member216 comprises a substantially convex bearing surface 234 and a proximalsurface 235 opposite thereto. As shown, the proximal surface 235 isgenerally planar, but it is also contemplated that it could benon-planar. The bearing surface 234 is adapted to emulate the generalshape and function of the head portion of the metatarsal bone within ametatarsophalangeal joint. The metatarsal articulation member 216 alsocomprises a cavity 236 depressed from the center (not labeled) of theproximal surface 235 and that is adapted to receive at least a portionof the combination of the screw member 219 and base member 218. In someembodiments, the cavity 236 is adapted to receive at least a portion ofthe head portion 222 of the base member 218 and at least a portion ofthe head portion 230 of the screw member 219 when the screw member 219is received within the cavity 223 of the base member 218. The cavity 236of the metatarsal articulation member 216 comprises a distal portion 237for receiving at least a portion of the head portion 230 of the screwmember 219, a middle portion 238 for receiving the second end 221 and atleast a portion of the head portion 222 of the base member 218, and aproximal portion 239 for receiving at least a portion of the flanges ofthe locking member 225. The distal portion 237 of the cavity 236 has across-section that matches that of the head portion 230 of the screwmember 219. As shown, the distal portion 237 has a circularcross-section. The middle portion 238 of the cavity 236 has across-section that matches that of the second end 221 and at least aportion of the head portion 222 of the base member 218. As shown, themiddle portion 238 has a rectangular cross-section. The proximal portion239 of the cavity 236 comprises at least two opposing slots adapted toreceive at least a portion of the opposing flanges of the locking member225. As shown, the slots of the proximal portion 239 have a rectangularcross-section.

As also illustrated in FIG. 22, the phalanx articulation member 217comprises a substantially concave bearing surface 240 and a distalsurface 241 opposite thereto. As shown, the distal surface 241 isgenerally planar, but it is also contemplated that it could benon-planar. The bearing surface 240 is adapted to emulate the generalshape and function of the proximal portion of the proximal phalanx bonewithin a metatarsophalangeal joint. The phalanx articulation member 217also comprises a cavity 242 depressed from the center (not labeled) ofthe distal surface 241 and that is adapted to receive at least a portionof the combination of the screw member 219 and base member 218. In someembodiments, the cavity 242 is adapted to receive at least a portion ofthe head portion 222 of the base member 218 and at least a portion ofthe head portion 230 of the screw member 219 when the screw member 219is received within the cavity 223 of the base member 218. The cavity 242of the phalanx articulation member 217 comprises a proximal portion 243for receiving at least a portion of the head portion 230 of the screwmember 219, a middle portion 244 for receiving the second end 221 and atleast a portion of the head portion 222 of the base member 218, and adistal portion 245 for receiving at least a portion of the flanges ofthe locking member 225. The proximal portion 243 of the cavity 242 has across-section that matches that of the head portion 230 of the screwmember 219. As shown, the distal portion 243 has a circularcross-section. The middle portion 244 of the cavity 242 has across-section that matches that of the second end 221 and at least aportion of the head portion 222 of the base member 218. As shown, themiddle portion 244 has a rectangular cross-section. The distal portion245 of the cavity 242 comprises at least two opposing slots adapted toreceive at least a portion of the opposing flanges of the locking member225. As shown, the slots of the distal portion 245 have a rectangularcross-section.

In some embodiments, at least a portion of the metatarsal articulationmember 216, at least a portion of the flanges of the locking member 225,or combinations thereof are suitably flexible such that the flanges 225may be received within the proximal portion 239 of the cavity 236 of thearticulation member 216 to mechanically join the articulation member 216with the base member 218. In some embodiments, at least a portion of thephalanx articulation member 217, at least a portion of the flanges ofthe locking member 225, or combinations thereof are suitably flexiblesuch that the flanges may be received within the distal portion 245 ofthe cavity 242 of the articulation member 217 to mechanically join thearticulation member 217 with the base member 218.

In some embodiments of assembly, at least the first end 220 and bodyportion 223 of the base member 218 are first implanted within theresected portion of the bone. Then the first end 228 of the screw member219 is inserted in and, using a tool that fits the slot 233 of the screwmember 219, screwed through the second end 221 and head portion 222 ofthe base member 218, thereby causing the body portion 223 of the basemember 218 to expand with sufficient force to fix the base member 218and screw member 219 within the bone. When so fixed, the head portion230 of the screw member 219 abuts the second end 221 of the base member218. Next, either the metatarsal articulation member 216 or the phalanxarticulation member 217 is placed over the combined locking head portion230, base second end 221, and base head portion 222 in an orientationallowing the flanges of the locking member 225 to be received within theslots 239 or 245 of the chosen articulation member 216 or 217. Finally,sufficient force is applied to the chosen articulation member 216 or 217to cause at least a portion of the articulation member 216 or 217, thelocking member 225, or combinations thereof to resiliently flex from afirst to a second position to allow the flanges to be received withinthe slots 239 or 245, and then from a second to a first position as theflanges are received within the slots 239 or 245. Alternatively, it iscontemplated that at least a portion of the articulation member 216 or217, the locking member 225, or combinations thereof may resilientlyflex from the second to an intermediate third configuration as theflanges are received within the slots 239 or 245. When the flanges arereceived within the slots 239 or 245, the chosen articulation member 216or 217 is mechanically joined to the base member 218. In someembodiments, the chosen articulation member 216 or 217 is permanentlyjoined to the base member 218.

Referring to FIGS. 23-25, illustrated is one example of a devicecomprising a metatarsal articulation member 246, a phalanx articulationmember 247, a base member 248, and a locking member 249. The device maybe utilized as a single (hemi) component implant or as a two-component(total) implant. The base member 248 is designed to be implanted intothe distal end of a resected metatarsal bone, the proximal end of aresected proximal phalanx bone, or both. The base member 248 may be ofany suitable length and dimension to allow for fixation within themetatarsal and phalanx bones, and may be fixed by any medically suitablemeans. In some embodiments, the base member 248 is designed to beimplanted in approximately one third of the length of the metatarsalbone or half of the length of the phalanx bone. In some embodiments, itis designed to be fixed by tension on the interior cavity of theresected bone. When the metatarsal-implanted base member 248 ismechanically joined to the metatarsal articulation member 246 with thelocking member 249, the device is designed to replace all or a portionof the metatarsal head and function as the metatarsal component of themetatarsophalangeal joint. When the phalanx-implanted base member 248 ismechanically joined to the phalanx articulation member 247 with thelocking member 249, the device is designed to replace all or a portionof the proximal end of the proximal phalanx and function as the phalanxcomponent of the metatarsophalangeal joint.

In some embodiments, the device may be implanted into one or both of themetatarsal and phalanx bones in a primary resectional arthroplastyprocedure, in a revision arthroplasty procedure performed to replace orcompensate for a failed implant, or combinations thereof. In someembodiments, implantation is by a revision arthroplasty procedure. Insome embodiments, each device implanted may be selected from small,medium, or large sizes as necessary to approximate the anatomy of thesubject. In some embodiments, the devices may comprise one or moredimensions set forth in Table 7. In some embodiments, each device andelements thereof may be customized to the anatomy of the subject.

TABLE 7 Dimension Metatarsal and Phalanx (mm) Base Member LengthMetatarsal 22-26 Base Member Length Phalange 18-22 Locking Member LengthMetatarsal 22-26 Locking Member Length Phalange 18-22 Locking MemberHead Height 2 Locking Member Head Diameter 9-10 Articulation MemberHeight 10  (Excluding Bearing Surface) Articulation Member Dome Diameter16-22 Phalanx Bearing Surface Depth 2 Metatarsal Bearing Surface Height2

A further illustrated in FIG. 24, the base member 248 comprises a firstend 250, a second end 251 comprising a head portion 252, a body portion253, and a cavity 254 for receiving the locking member 249. As shown,the first 250 and second 251 ends are non-continuous. The cavity 254 iscontinuous through the base member 248 from the first end 250 to thesecond end 251. As shown, the cavity 254 and body portion 253 areconical or tapered and have a generally non-continuous cross-sectionwith a generally circular shape. It is, however, contemplated that thecavity 254 and body portion 253 could alternatively be non-conical ornon-tapered, have another suitable cross-section, or combinationsthereof, provided that other elements of the device are also adapted tofit such alternatives. For example, a cross-section could be selectedfrom generally elliptical, square, or other suitable shape. In someembodiments, the body portion 253 may be a resilient member adapted tobe received within the interior cavity of a resected bone, wherein thebody portion 253 expands in response to the locking member 249 beingreceived and advanced through the cavity 254 and exerts sufficienttension on the cavity of the bone to fix the base member 248 therein. Insome embodiments, the body portion 253 may comprise a resilient materialsuitable for surgical implants.

The head portion 252 has a generally circular cross-section. However, itis also contemplated that a head portion 252 could alternatively haveanother suitable cross-section, provided that other elements of thedevice are also adapted to fit such alternatives. For example, a headportion 252 could have a cross-section selected from generallyelliptical, square, or other suitable shape. The head portion 252 alsocomprises an interior (female) screw thread 255 along the portion of thecavity 254 formed within the head portion 252, said screw thread 255adapted to receive a portion of the locking member 249.

As shown, the locking member 249 is a screw member comprising a firstend 256, a second end 257 comprising a head portion 258, and a bodyportion 259 comprising an external (male) screw thread 260. The screwthread 260 is adapted to be at least partially received by the interiorscrew thread 255 of the base member 248. The locking member 249 isgenerally cylindrical and has a generally circular cross-section.However, it is also contemplated that the locking member 249 couldalternatively be non-cylindrical, have an different cross-section, orcombinations thereof, provided that other elements of the device arecorrespondingly adapted. For example, a locking member 249 could betapered or conical or have a helical cross-section. The head portion 258of the locking member 249 has a cross-section larger than that of thebody portion 259. Additionally, the head portion 258 comprises a slot261 centrally positioned on the second end 257 and an external (male)screw thread 262. The screw thread 262 is adapted to be at leastpartially received by a portion of the metatarsal articulation member246, phalanx articulation member 247, or both. As shown, the slot 261has a generally rectangular cross-section. However, it is alsocontemplated that the slot 261 could alternatively have another suitablecross-section. The locking member 249 is adapted to be received withinthe cavity 254 of the base member 248. When the locking member 249 is soreceived, the head portion 258 abuts the second end 251 of the basemember 248. It is also contemplated that the head portion 258 could bespaced from the second end 251 when so received. The combination of thelocking member 249 and base member 248 is adapted be at least partiallyreceived by the metatarsal articulation member 246, the phalanxarticulation member 247, or both.

As further illustrated in FIG. 25, the metatarsal articulation member246 comprises a substantially convex bearing surface 263 and a proximalsurface 264 opposite thereto. As shown, the proximal surface 264 isgenerally planar, but it is also contemplated that it could benon-planar. The bearing surface 263 is adapted to emulate the generalshape and function of the head portion of the metatarsal bone within ametatarsophalangeal joint. The metatarsal articulation member 246 alsocomprises a cavity 265 depressed from the center (not labeled) of theproximal surface 264. The cavity 265 comprises an interior (female)screw thread 266 adapted to receive at least a portion of the externalscrew thread 262 of the head portion 258 of the locking member 249. Insome embodiments, all of the head portion 258 may be received within thecavity 265. The cavity 265 has a cross-section that matches that of thehead portion 258 of the locking member 249. As shown, the cavity 265 hasa circular cross-section.

As additionally illustrated in FIG. 25, the phalanx articulation member247 comprises a substantially concave bearing surface 267 and a distalsurface 268 opposite thereto. As shown, the distal surface 268 isgenerally planar, but it is also contemplated that it could benon-planar. The bearing surface 267 is adapted to emulate the generalshape and function of the proximal portion of the proximal phalanx bonewithin a metatarsophalangeal joint. The phalanx articulation member 247also comprises a cavity 269 depressed from the center (not labeled) ofthe distal surface 268. The cavity 269 comprises an interior (female)screw thread 270 adapted to receive at least a portion of the externalscrew thread 262 of the head portion 258 of the locking member 249. Insome embodiments, all of the head portion 258 may be received within thecavity 269. The cavity 269 has a cross-section that matches that of thehead portion 258 of the locking member 249. As shown, the cavity 269 hasa circular cross-section.

In some embodiments of assembly, at least the first end 250 and bodyportion 253 of the base member 248 are first implanted within theresected portion of the bone. Then the first end 256 of the lockingmember 249 is inserted in and, using a tool that fits the slot 261 ofthe locking member 249, screwed through the second end 251 and headportion 252 of the base member 248, thereby causing the body portion 253of the base member 248 to expand with sufficient force to fix the basemember 248 and locking member 249 within the bone cavity. When so fixed,the head portion 258 of the locking member 249 abuts or is proximate tothe second end 251 of the base member 248. Next, either the metatarsalarticulation member 246 or the phalanx articulation member 247 is placedover the head portion 258 of the locking member 249 such that the headportion 258 may be received within the cavity 265 or 269 of the chosenarticulation member 246 or 247. Finally, the chosen articulation member246 or 247 is screwed onto the head portion 258 of the locking member249 to mechanically join the articulation member chosen 246 or 247 withthe base member 248.

Referring to FIGS. 26-27, illustrated is an example of an implantabledevice of the invention which is designed to replace all or a portion ofa metatarsophalangeal joint. Such device comprises one or more of: (i) ametatarsal component for surgical implantation into the distal end of ametatarsal bone, comprising a metatarsal articulation member comprisinga substantially convex bearing surface; and a locking member comprisinga screw thread adapted to fix the metatarsal component in the metatarsalbone; and (ii) a phalanx component for surgical implantation into theproximal end of a proximal phalanx bone, comprising a phalanxarticulation member comprising a substantially concave bearing surface;and a locking member comprising a screw thread adapted to fix thephalanx component in the phalanx bone.

In those embodiments wherein one of the components is implanted, thechosen component is adapted to cooperatively engage with and move withrespect to either the proximal end of the proximal phalanx bone or thedistal end of the metatarsal bone. In those embodiments wherein both ofthe components are implanted, the metatarsal component and the phalanxcomponent are adapted to cooperatively engage such that the metatarsalarticulation member and the phalanx articulation member move withrespect to each other and collectively serve as a prostheticmetatarsophalangeal joint.

As illustrated in FIG. 26, the two-component device 271 comprises ametatarsal component 272 designed to be implanted into the distal end ofa resected metatarsal bone, and a phalanx component 273 designed to beimplanted into the proximal end of a resected proximal phalanx bone. Themetatarsal component 272 may be of any suitable length and dimension toallow for fixation within the metatarsal bone, and may be fixed by anymedically suitable means. In some embodiments, the metatarsal component272 is designed to be implanted in approximately one third of the lengthof the metatarsal bone. The phalanx component 273 may be of any suitablelength and dimension to allow for fixation within the phalanx bone, andmay be fixed by any medically suitable means. In some embodiments, thephalanx component 273 is designed to be implanted in approximately halfof the length of the phalanx bone.

In some embodiments, the components 272, 273 may be implanted into oneor both of the metatarsal and phalanx bones in a primary resectionalarthroplasty procedure, in a revision arthroplasty procedure performedto replace or compensate for a failed implant, or combinations thereof.In some embodiments, implantation is by a primary arthroplastyprocedure. In some embodiments, each device implanted may be selectedfrom small, medium, or large sizes as necessary to approximate theanatomy of the subject. In some embodiments, the components 272, 273 maycomprise one or more dimensions set forth in Table 8. In someembodiments, each device and elements thereof may be customized to theanatomy of the subject.

TABLE 8 Dimension Metatarsal and Phalanx (mm) Total Length Metatarsal22-26 Total Length Phalange 18-22 Locking Member Length Metatarsal 22-26Locking Member Length Phalange 18-22 Locking Member Head Height 2 ScrewHead Diameter 10-13 Articulation Member Height 10  (Excluding BearingSurface) Phalanx Bearing Surface Depth 3 Metatarsal Bearing SurfaceHeight 3

As further illustrated in FIG. 27, the metatarsal component 272comprises a first end 274, a second end 275 comprising a metatarsalarticulation member 276, and a locking member 277 comprising an external(male) screw thread 278. The screw thread 278 is adapted to be at leastpartially received within, and fix the metatarsal component 272 to, aresected distal end of a metatarsal bone. The locking member 277 isgenerally cylindrical and has a generally circular cross-section.However, it is also contemplated that the locking member 277 couldalternatively be non-cylindrical, have an different cross-section, orcombinations thereof. For example, a locking member 277 could be taperedor conical or have a helical cross-section. The articulation member 276of the metatarsal component 272 has a cross-section larger than that ofthe locking member 277. Additionally, the metatarsal articulation member276 comprises a substantially convex bearing surface 279. The bearingsurface 279 is adapted to emulate the general shape and, when implantedinto the resected metatarsal bone, function of the head portion of themetatarsal bone within a metatarsophalangeal joint.

As additionally illustrated in FIG. 27, the phalanx component 273comprises a first end 280, a second end 281 comprising a phalanxarticulation member 282, and a locking member 283 comprising an external(male) screw thread 284. The screw thread 284 is adapted to be at leastpartially received within, and fix the phalanx component 273 to, aresected proximal end of a proximal phalanx bone. The locking member 283is generally cylindrical and has a generally circular cross-section.However, it is also contemplated that the locking member 283 couldalternatively be non-cylindrical, have an different cross-section, orcombinations thereof. For example, a locking member 283 could be taperedor conical or have a helical cross-section. The articulation member 282of the phalanx component 273 has a cross-section larger than that of thelocking member 283. Additionally, the phalanx articulation member 282comprises a substantially concave bearing surface 285. The bearingsurface 285 is adapted to emulate the general shape and, when implantedinto the resected proximal phalanx bone, function of the proximalportion of the proximal phalanx bone within a metatarsophalangeal joint.

In some embodiments of operation, at least the first end 274 and lockingmember 277 of the metatarsal component 272 are inserted in and screwedinto the distal end of a resected metatarsal bone. In some embodiments,at least all of the locking member 277 is screwed into the metatarsalbone. In some embodiments, all of the locking member 277 and at least aportion of the metatarsal articulation member 276 are implanted into themetatarsal bone. In some embodiments, a portion (“screw head”) of themetatarsal articulation member 276 proximate to the locking member 277may be received within the resected bone. In some embodiments ofoperation, at least the first end 280 and locking member 283 of thephalanx component 273 are inserted in and screwed into the proximal endof a resected proximal phalanx bone. In some embodiments, at least allof the locking member 283 is screwed into the proximal phalanx bone. Insome embodiments, all of the locking member 283 and at least a portionof the phalanx articulation member 282 are implanted into the proximalphalanx bone. In some embodiments, a portion (“screw head”) of thephalanx articulation member 282 proximate to the locking member 283 maybe received within the resected bone.

Referring to FIGS. 28-30, illustrated is an example of an implantabledevice of the invention which is designed to replace all or a portion ofa metatarsophalangeal joint. Such device comprises one or more of: (i) ametatarsal component for surgical implantation into the distal end of ametatarsal bone, comprising a metatarsal articulation member comprisinga substantially convex parabolic bearing surface terminating atequidistantly positioned ends; and (ii) a phalanx component for surgicalimplantation into the proximal end of a proximal phalanx bone,comprising a phalanx articulation member comprising a substantiallyconcave bearing surface.

In those embodiments wherein one of the components is implanted, thechosen component is adapted to cooperatively engage with and move withrespect to either the proximal end of the proximal phalanx bone or thedistal end of the metatarsal bone. In those embodiments wherein both ofthe components are implanted, the metatarsal component and the phalanxcomponent are adapted to cooperatively engage such that the metatarsalarticulation member and the phalanx articulation member move withrespect to each other and collectively serve as a prostheticmetatarsophalangeal joint.

As illustrated, the two-component device 286 comprises a metatarsalcomponent 287 and a phalanx component 288. The metatarsal component 287is designed to be implanted into the distal end of a resected metatarsalbone to replace all or a portion of the metatarsal head and function asthe metatarsal component of the metatarsophalangeal joint. The phalanxcomponent 288 is designed to be implanted into the proximal end of theproximal phalanx and function as the phalanx component of themetatarsophalangeal joint.

In some embodiments, the components 287, 288 may be implanted into oneor both of the metatarsal and phalanx bones in a primary resectionalarthroplasty procedure, in a revision arthroplasty procedure performedto replace or compensate for a failed implant, or combinations thereof.In some embodiments, implantation is by a revision arthroplastyprocedure. In some embodiments, each device implanted may be selectedfrom small, medium, or large sizes as necessary to approximate theanatomy of the subject. In some embodiments, the components 287, 288 maycomprise one or more of the dimensions set forth in Table 9. In someembodiments, each device and elements thereof may be customized to theanatomy of the subject.

TABLE 9 Dimension (mm) Metatarsal Stem Length 10-11 Stem Diameter 5-6Articulation Member Width 18-19 Articulation Member Diameter 12-14Phalanx Stem Length 10-11 Stem Diameter 5-6 Articulation Member Height16-18 Articulation Member Width 20-21 Articulation Member Diameter 12-14

In some embodiments, the material of composition of the components 287,288 is pyrocarbon. In some embodiments, the material of composition ispyrocarbon having a coating to enhance bone growth. In some embodiments,the coating is titanium plasma spray.

As further illustrated in FIG. 29, the metatarsal component 287comprises a metatarsal articulation member 289, a stem 290, and aproximal end 291. The metatarsal articulation member 289 comprises asubstantially convex bearing surface 292 having a paraboliccross-section and a proximal surface 293 opposite thereto. In someembodiments, the proximal surface 293 has a semi-circular cross-section.However, alternative cross-sections are also contemplated. For example,semi-elliptical, semi-oval, or parabolic cross-sections. In someembodiments, the convex bearing surface 292 and proximal surface 293comprise shared ends 294 that are equidistantly positioned with respectto each other. In some embodiments, the ends 294 are equidistantlyposition with respect to each other and the stem 290. The bearingsurface 292 is adapted to emulate the general shape and function as thehead portion of the metatarsal bone within a metatarsophalangeal joint.

The stem 290 protrudes from the center (not labeled) of the proximalsurface 293, terminates at the proximal end 291, and is adapted to bereceived within a resected metatarsal bone. As shown, the stem 290 isconical or tapered and has a circular cross-section. In someembodiments, the stem 290 is tapered and has a taper angle of from about0-10°. However, it is also contemplated that the stem 290 couldalternatively be non-conical or non-tapered, have another suitablecross-section, or combinations thereof. For example, a stem 290 could becylindrical, have a cross-section selected from generally elliptical,square, triangular, or other suitable shape, or combinations thereof.The stem 290 may be of any suitable length and dimension to allow forfixation within the metatarsal bone, and may be fixed by any medicallysuitable means. In some embodiments, the stem 290 is designed to beimplanted in approximately one third of the length of the metatarsalbone. In some embodiments, it may be fixed with bone cement.

In some embodiments of operation, the proximal end 291 and at least aportion of the stem 290 of the metatarsal component 287 are implantedinto the distal end of a resected metatarsal bone. In some embodimentsof operation, the proximal end 291 and the entire stem 290 are implantedsuch that the proximal surface 293 abuts the distal end of the resectedmetatarsal bone. In some embodiments, the metatarsal component 287 isdesigned to be implanted without a washer or other spacer means betweenthe proximal surface 293 and the bone.

As further illustrated in FIG. 30, the phalanx component 288 comprises aphalanx articulation member 295, a stem 296, and a distal end 297. Thephalanx articulation member 295 comprises a substantially concavebearing surface 298 and a distal surface 299 opposite thereto. As shown,the distal surface 299 is generally planar, but it is also contemplatedthat it could be non-planar. Moreover, as shown, the phalanxarticulation member 295 has a generally elliptical cross-section. It iscontemplated, however, that it could have another suitablecross-section, provided that the metatarsal component 287 iscorrespondingly adapted to enable cooperative engagement. The bearingsurface 298 is adapted to emulate the general shape and function as theproximal portion of the proximal phalanx bone within ametatarsophalangeal joint. The stem 296 protrudes from the center (notlabeled) of the distal surface 299, terminates at the distal end 297,and is adapted to be received within a resected proximal phalanx bone.As shown, the stem 296 is conical or tapered and has a circularcross-section. In some embodiments, the stem 296 is tapered and has ataper angle of from about 0-10°. However, it is also contemplated thatthe stem 296 could alternatively be non-conical or non-tapered, haveanother suitable cross-section, or combinations thereof. For example, astem 296 could be cylindrical, have a cross-section selected fromgenerally elliptical, square, triangular, or other suitable shape, orcombinations thereof. The stem 296 may be of any suitable length anddimension to allow for fixation within the phalanx bone, and may befixed by any medically suitable means. In some embodiments, the stem 296is designed to be implanted in approximately half of the length of thephalanx bone. In some embodiments, it may be fixed with bone cement.

In some embodiments of operation, the distal end 297 and at least aportion of the stem 296 of the phalanx component 288 are implanted intothe proximal end of a resected proximal phalanx bone. In someembodiments of operation, the distal end 297 and the entire stem 296 areimplanted such that the distal surface 299 abuts the proximal end of theresected proximal phalanx bone. In some embodiments, the phalanxcomponent 288 is designed to be implanted without a washer or otherspacer means between the distal surface 299 and the bone.

In various embodiments, provided are methods of treating hallux valgus,comprising replacing all or a portion of a metatarsophalangeal jointwith implantable devices selected from: (i) a metatarsal component forsurgical implantation into the distal end of a metatarsal bone,comprising a metatarsal articulation member comprising a substantiallyconvex bearing surface; (ii) a phalanx component for surgicalimplantation into the proximal end of a proximal phalanx bone,comprising a phalanx articulation member comprising a substantiallyconcave bearing surface; or (iii) a metatarsal component for surgicalimplantation into the distal end of a metatarsal bone, comprising ametatarsal articulation member comprising a substantially convex bearingsurface; and a phalanx component for surgical implantation into theproximal end of a proximal phalanx bone, comprising a phalanxarticulation member comprising a substantially concave bearing surface.In some embodiments, the provided methods may be used to correct one ormore of the hallus valgus angle and the intermetatarsal angle. In someembodiments, the provided methods may be used to provide a subject withalignment and articulation of the metatarsal and proximal phalanx bonesin a manner consistent with that of a natural metatarsophalangeal joint.In some embodiments, the provided methods may be performed withoutcomplex assembly, positioning, or other manipulation of the implantdevice by the surgeon. In some embodiments, one or more of the devicesillustrated in FIGS. 2-30 and further described herein may be utilizedwith the provided methods.

1. An implantable device for replacing all or a portion of ametatarsophalangeal joint, comprising: (i) a metatarsal component forsurgical implantation into the distal end of a metatarsal bone,comprising: a metatarsal articulation member comprising a substantiallyconvex bearing surface; a base member adapted to be fixed within themetatarsal bone; and a locking member adapted to mechanically join themetatarsal articulation member to the base member; (ii) a phalanxcomponent for surgical implantation into the proximal end of a proximalphalanx bone, comprising: a phalanx articulation member comprising asubstantially concave bearing surface; a base member adapted to be fixedwithin the phalanx bone; and a locking member adapted to mechanicallyjoin the phalanx articulation member to the base member; wherein themetatarsal component and the phalanx component are adapted tocooperatively engage when implanted such that the metatarsalarticulation member and the phalanx articulation member may move withrespect to each other and collectively serve as a prostheticmetatarsophalangeal joint.
 2. A device according to claim 1, comprisinga material of composition selected from ultra-high molecular weightpolyethylene, stainless steel, titanium, titanium alloy,chromium-cobalt-molybdenum alloy, pyrocarbon, and combinations thereof.3. An implantable device for replacing all or a portion of ametatarsophalangeal joint, comprising: (i) a metatarsal component forsurgical implantation into the distal end of a metatarsal bone,comprising: a metatarsal articulation member comprising a substantiallyconvex bearing surface and a stem adapted to receive a portion of alocking member; a base member adapted to be fixed within the metatarsalbone, the base member comprising a cavity adapted to receive at least aportion of the stem and a portion of the locking member; and a lockingmember adapted to be received by the stem and cavity; wherein when thestem is received in the cavity and the locking member is received by thestem and cavity, the metatarsal articulation member is mechanicallyjoined to the base member; (ii) a phalanx component for surgicalimplantation into the proximal end of a proximal phalanx bone,comprising: a phalanx articulation member comprising a substantiallyconcave bearing surface and a stem adapted to receive a portion of alocking member; a base member adapted to be fixed within the phalanxbone, the base member comprising a cavity adapted to receive at least aportion of the stem and a portion of the locking member; and a lockingmember adapted to be received by the stem and cavity; wherein when thestem is received in the cavity and the locking member is received by thestem and cavity, the phalanx articulation member is mechanically joinedto the base member; wherein the metatarsal component and the phalanxcomponent are adapted to cooperatively engage when implanted such thatthe metatarsal articulation member and the phalanx articulation membermay move with respect to each other and collectively serve as aprosthetic metatarsophalangeal joint.
 4. A device according to claim 3,wherein at least one of the stem of the metatarsal component and thestem of the phalanx component comprises a slot adapted to receive atleast a portion of a locking member.
 5. A device according to claim 4,wherein at least one of the cavity of the metatarsal component and thecavity of the phalanx component comprises a slot adapted to receive atleast a portion of a locking member.
 6. A device according to claim 4,wherein the locking member is a flexible spring member adapted to bereceived within the slot of an articulation member and the slot of abase member of a metatarsal component or a phalanx component.
 7. Adevice according to claim 3, wherein the base member of the metatarsalcomponent, the base member of the phalanx component, or both have ashape selected from cylindrical, conical, or tapered.
 8. A deviceaccording to claim 7, wherein at least one of the base members comprisesone or more peripherally positioned flanges adapted to be receivedwithin a cavity of a resected bone.
 9. A device according to claim 8,wherein the flanges are flexible spring members that, when inserted intothe cavity, exert sufficient tension to fix the base member within thebone.
 10. A device according to claim 9, comprising four equidistantlongitudinally positioned flanges.
 11. A device according to claim 3,comprising a material of composition selected from ultra-high molecularweight polyethylene, stainless steel, titanium, titanium alloy,chromium-cobalt-molybdenum alloy, pyrocarbon, and combinations thereof.12. An implantable device for replacing all or a portion of ametatarsophalangeal joint, comprising: (i) a metatarsal component forsurgical implantation into the distal end of a metatarsal bone,comprising: a metatarsal articulation member comprising a substantiallyconvex bearing surface and a locking member; a base member adapted to befixed within the metatarsal bone, the base member comprising a cavityadapted to receive the locking member; wherein when the locking memberis received by the cavity, the metatarsal articulation member ismechanically joined to the base member; (ii) a phalanx component forsurgical implantation into the proximal end of a proximal phalanx bone,comprising: a phalanx articulation member comprising a substantiallyconcave bearing surface and a locking member; a base member adapted tobe fixed within the phalanx bone, the base member comprising a cavityadapted to receive the locking member; wherein when the locking memberis received by the cavity, the phalanx articulation member ismechanically joined to the base member; wherein the metatarsal componentand the phalanx component are adapted to cooperatively engage whenimplanted such that the metatarsal articulation member and the phalanxarticulation member may move with respect to each other and collectivelyserve as a prosthetic metatarsophalangeal joint.
 13. A device accordingto claim 12, wherein the base member of the metatarsal component, thebase member of the phalanx component, or both have a shape selected fromcylindrical, conical, or tapered.
 14. A device according to claim 13,wherein at least one of the base members comprises one or moreperipherally positioned flanges adapted to be received within a cavityof a resected bone.
 15. A device according to claim 14, wherein theflanges are flexible spring members that, when inserted into the cavity,exert sufficient tension to fix the base member within the bone.
 16. Adevice according to claim 15, comprising four equidistant longitudinallypositioned flanges.
 17. A device according to claim 12, comprising amaterial of composition selected from ultra-high molecular weightpolyethylene, stainless steel, titanium, titanium alloy,chromium-cobalt-molybdenum alloy, pyrocarbon, and combinations thereof.18. An implantable device for replacing all or a portion of ametatarsophalangeal joint, comprising: (i) a metatarsal component forsurgical implantation into the distal end of a metatarsal bone,comprising: a metatarsal articulation member comprising a substantiallyconvex bearing surface and a cavity adapted to receive at least aportion of a locking member; a base member adapted to be fixed withinthe metatarsal bone, comprising a head portion, a body portion, and acontinuous cavity; and a locking member adapted to be at least partiallyreceived by the metatarsal articulation member cavity; wherein when thelocking member is received within the metatarsal articulation membercavity, the metatarsal articulation member is mechanically joined to thebase member; (ii) a phalanx component for surgical implantation into theproximal end of a proximal phalanx bone, comprising: a phalanxarticulation member comprising a substantially convex bearing surfaceand a cavity adapted to receive at least a portion of a locking member;a base member adapted to be fixed within the phalanx bone, comprising ahead portion, a body portion, and a continuous cavity; and a lockingmember adapted to be at least partially received by the phalanxarticulation member cavity; wherein when the locking member is receivedwithin the phalanx articulation member cavity, the phalanx articulationmember is mechanically joined to the base member; wherein the metatarsalcomponent and the phalanx component are adapted to cooperatively engagewhen implanted such that the metatarsal articulation member and thephalanx articulation member may move with respect to each other andcollectively serve as a prosthetic metatarsophalangeal joint.
 19. Adevice according to claim 18, wherein the body portion of the metatarsalcomponent, the body portion of the phalanx component, or both have ashape selected from cylindrical, conical, or tapered.
 20. A deviceaccording to claim 18, wherein the continuous cavity of the metatarsalcomponent, the continuous cavity of the phalanx component, or both isadapted to receive a screw member that, when received within thecontinuous cavity, causes the body portion to expand and exertsufficient tension to fix the base member within the bone.
 21. A deviceaccording to claim 20, wherein the locking member is at least a portionof the screw member.
 22. A device according to claim 20, wherein thelocking member is at least one pair of flanges opposably positioned onthe head portion.
 23. A device according to claim 20, comprising amaterial of composition selected from ultra-high molecular weightpolyethylene, stainless steel, titanium, titanium alloy,chromium-cobalt-molybdenum alloy, pyrocarbon, and combinations thereof.24. An implantable device for replacing all or a portion of ametatarsophalangeal joint, comprising: (i) a metatarsal component forsurgical implantation into the distal end of a metatarsal bone,comprising: a metatarsal articulation member comprising a substantiallyconvex bearing surface; and a locking member comprising a screw threadadapted to fix the metatarsal component in the metatarsal bone; (ii) aphalanx component for surgical implantation into the proximal end of aproximal phalanx bone, comprising: a phalanx articulation membercomprising a substantially concave bearing surface; and a locking membercomprising a screw thread adapted to fix the phalanx component in thephalanx bone; wherein the metatarsal component and the phalanx componentare adapted to cooperatively engage when implanted such that themetatarsal articulation member and the phalanx articulation member maymove with respect to each other and collectively serve as a prostheticmetatarsophalangeal joint.
 25. A device according to claim 24,comprising a material of composition selected from ultra-high molecularweight polyethylene, stainless steel, titanium, titanium alloy,chromium-cobalt-molybdenum alloy, pyrocarbon, and combinations thereof.26. An implantable device for replacing all or a portion of ametatarsophalangeal joint, comprising: (i) a metatarsal component forsurgical implantation into the distal end of a metatarsal bone,comprising: a metatarsal articulation member comprising a substantiallyconvex parabolic bearing surface terminating at equidistantly positionedends; (ii) a phalanx component for surgical implantation into theproximal end of a proximal phalanx bone, comprising: a phalanxarticulation member comprising a substantially concave bearing surface;wherein the metatarsal component and the phalanx component are adaptedto cooperatively engage when implanted such that the metatarsalarticulation member and the phalanx articulation member may move withrespect to each other and collectively serve as a prostheticmetatarsophalangeal joint.
 27. A device according to claim 26,comprising a material of composition selected from ultra-high molecularweight polyethylene, stainless steel, titanium, titanium alloy,chromium-cobalt-molybdenum alloy, pyrocarbon, and combinations thereof.28. A method of treating hallux valgus, comprising surgically replacinga metatarsophalangeal joint with an implantable device selected from:(I) an implantable two-component device comprising: (i) a metatarsalcomponent for surgical implantation into the distal end of a metatarsalbone, comprising: a metatarsal articulation member comprising asubstantially convex bearing surface; a base member adapted to be fixedwithin the metatarsal bone; and a locking member adapted to mechanicallyjoin the metatarsal articulation member to the base member; and (ii) aphalanx component for surgical implantation into the proximal end of aproximal phalanx bone, comprising: a phalanx articulation membercomprising a substantially concave bearing surface; a base memberadapted to be fixed within the phalanx bone; and a locking memberadapted to mechanically join the phalanx articulation member to the basemember; wherein the metatarsal component and the phalanx component areadapted to cooperatively engage when implanted such that the metatarsalarticulation member and the phalanx articulation member may move withrespect to each other and collectively serve as a prostheticmetatarsophalangeal joint; (II) an implantable two-component devicecomprising: (i) a metatarsal component for surgical implantation intothe distal end of a metatarsal bone, comprising: a metatarsalarticulation member comprising a substantially convex bearing surface;and a locking member comprising a screw thread adapted to fix themetatarsal component in the metatarsal bone; (ii) a phalanx componentfor surgical implantation into the proximal end of a proximal phalanxbone, comprising: a phalanx articulation member comprising asubstantially concave bearing surface; and a locking member comprising ascrew thread adapted to fix the phalanx component in the phalanx bone;wherein the metatarsal component and the phalanx component are adaptedto cooperatively engage when implanted such that the metatarsalarticulation member and the phalanx articulation member may move withrespect to each other and collectively serve as a prostheticmetatarsophalangeal joint; and (III) an implantable two-component devicecomprising: (i) a metatarsal component for surgical implantation intothe distal end of a metatarsal bone, comprising: a metatarsalarticulation member comprising a substantially convex parabolic bearingsurface terminating at equidistantly positioned ends; (ii) a phalanxcomponent for surgical implantation into the proximal end of a proximalphalanx bone, comprising: a phalanx articulation member comprising asubstantially concave bearing surface; wherein the metatarsal componentand the phalanx component are adapted to cooperatively engage whenimplanted such that the metatarsal articulation member and the phalanxarticulation member may move with respect to each other and collectivelyserve as a prosthetic metatarsophalangeal joint.